What your Electronic Power Control (EPC) Warning Light really means

Computers are ubiquitous or rather microcomputers, microprocessors and their peripheral systems and chipsets are.  As such, they can be found in most electronic devices, ranging from laptops to printers, routers, radios, walkie-talkies, cell-phones and toys to mention but a few. In fact, microprocessors are so common place that they've taken over most hand held and personal electronic devices so-much-so that they are even embedded in our entertainment equipment, our cars, motorcycles, aeroplanes, ships and trains. It can thus be said that electronics in all its technological forms, have completely changed how we live  our lives. These systems along with its sensors, sendors and actuators are referred to as On-Board Diagnostics (OBD) and since it's in its second revision, known as OBD-II or just OBDII.

Furthermore  these On-board diagnostic (OBDII) digital computers interfaced with its dependency modules, electro-mechanical systems and sensors built into our cars have collectively taken-over and superseded most mechanical linkage functions, that were previously and traditionally used for acceleration, steering control and parking brake among several other.  So, welcome to the world of  drive-by-wire, (electronic throttle control) steer-by-wire, shift-by-wire, brake-by-wire and fly-by-wire which is currently widely used in aviation. 

What your Electronic Power Control (EPC) Warning Light really says!

Your car's EPC light essentially indicates that there is an issue with the  torque system of your vehicle. This torque system is your car's acceleration and braking system that now operates via drive-by-wire, shift-by-wire and brake-by-wire. In a nutshell, it's a computer chip supervised electronic system (ECU) that replaced the cable linkage previously situated between the carburetor and the accelerator pedal with an electrical/electronic interface. 

This amber EPC light is an advisory light rather than a warning light -since warning lights are red in colour- is illuminated when the ECU detects a glitch in the torque system. When a glitch is detected, in most cases the ECU will enable 'limp home mode'. Limp mode is a fail-safe software-embedded, security and safety feature that  inhibits the system, activates a  rev limiter, shuts off boost partially or completely, resulting in a maximum 2500 RPM.  

Thereby leaving only sufficient power to safely drive the car home in some cases. In other cases it could prevent the car from even starting.  Limp mode also acts as a safe-guard against further engine / transmission trouble or possible runaway.  Switching off the engine and disconnecting the battery may in some cases momentarily cure limp mode, but then again it may not due to the ECU's  non-volatile memory. However as an  advisory light, it begs for an OBD-II diagnostic scan, so that the Trouble Code (DTC) error may be diagnosed and repaired. This is best done sooner rather than later, as Limp mode sometimes manages to cures itself, yet bound to repeat itself continually until repaired. The ECU has a counter / timer monitoring how many times the same DTC was detected since the last start-up. If just a few times (considered negligible / mistakenly triggered) the counter resets itself and starts to recount from when it happens again.

Having said that, EPC lights and drive-by-wire systems aren't exclusive to "VAG cars" like most mechanics would have you to believe. The EPC light is a mandatory part  of the OBD-II system hence fitted as standard equipment on "all post '96 cars". OBD regulations are written into Government legislation globally so that in time, the Department of Transport (DoT) may require all vehicles to regularly go for mandatory carbon emission tests in order the achieve road roadworthiness. They will access your cars under dash 16 pin obd connector to check its "Readiness Status". Readiness is an 2 x 4 digit binary number (hexadecimal) that look something like 1011 0110 or 1110 0101 or 0000 0000 or any combination of zeros and ones which is subject to the workings of equipment fitted in your vehicle.

Anyway, if you don't know, VAG stands for Volkswagen AG. The AG is an abbreviation for Aktiengesellschaft - implying incorporated. Aktiengesellschaft is the German term for a Public Limited Company (PLC). Thus the  VAG group is comprised of ten car brands  viz, Volkswagen, VW Commercial vehicles, Volkswagen Marine, Audi, SEAT, CUPRA, ŠKODA, Lamborghini, Porsche, Bentley and Ducati, spanning across five European countries.  In a nutshell most if not all these vehicles have a EPC light and torque control circuit operated via drive-by-wire as standard equipment. But as mentioned previously, an EPC lights with drive-by-wire and brake-by-wire is not exclusive to VAG cars.  

This torque circuit (throttle-by-wire) is a collection of interconnected electronic components amongst which are the car's battery, ignition switch, throttle body position sensor / potentiometer and throttle body actuator / stepper motor. The ECU itself, the braking system sensors and the wiring harnesses that supplies voltage / earth and feedback to and from the accelerator position sensor/ potentiometer and the throttle body motor, the cruise control switch, the instrument cluster and even one of the brake globes itself.

Possible problems

So by implication, with so many points of failure, so much can go wrong, For example, a loose battery terminal could cause the accelerator potentiometer input voltage to momentarily disappear for a fraction of a second, thus detected by the ECU which  would then trigger limp mode. It could also be caused by a speck of dust has settled on the potentiometer slider that creates a brief intermittent contact. The ECU will however detect this and implement limp mode. 

Then there is the dozens of wiring harnesses with their hundreds of connections. Several of them instrumental in the automotive torque circuit. Since electronics has taken over our cars, some having more than 3 dozen individual harnesses, collectively  comprising of more than 3000 wires and a third as many connectors. It gives you an idea of multitude of electrical problems that can occur.

Male and female wiring harness connectors used in the automotive industry are fairly reliable however due to the under-bonnet conditions like extreme engine heat and morning freezing temperatures, humidity, steam, condensation, oil splatter, dust and vibration, can collectively give rise to corrosion inside wired plugs and sockets. Corrosion normally causes high resistive electrical conditions which upsets the functionality of the circuit concerned.  

This could cause a myriad of problems in a myriad of circuits among which could be the MAF circuit, causing poor driveability and sudden jerking motions during acceleration flanked by untimed detonations.  It could be the MAP circuit causing poor fuel economy and difficult starting and rough idling. Catalytic converter wiring would cause dark exhaust smoke that  smell like rotten eggs due to the excess sulphur and the engine performance will be sluggish..... etc. Wait for the follow-up!

TRANSMISSION LIMP MODE

TRANSMISSION LIMP MODE 

During the late 1970's to the early 1980s, the on-board computer made its first appearance, responsible for monitoring and controlling the vehicle's engine. It started out with better fuel economy in mind,  followed by a  electronic capacitive discharge ignition systems (CDI), then electronic points and engine timing were introduced. Soon thereafter it encompassed anti-lock braking (ABS), airbags (SRS), climate control (HVAC), electronic stability control (ESP) and emissions control among several others. Today, virtually every subsystem in your vehicle is controlled by a computer  interfaced with sensors of sorts – including the automatic transmission’s shift timing sequence and line pressure.   The manifold absolute pressure (MAP) sensor and throttle position sensor (TPS), among several other, supplies the engine’s load signals and information which is used by the  Engine Control Unit (ECU) to inform the Transmission Control Unit (TCU) when to manage gear up-shift and down-shift, especially when you’re driving up an incline or inclined toward spirited driving. Since there is so much electronics, there is so much more that can go wrong,  so a  "fail safe" system had to be employed as a safety feature just in case of signal errors  that occur  outside of its expected range.  A feature that would protect the engine / transmission from "runaway" that could cause it to self destruct. 

There is even an Electronic Pressure Control (EPC) valve safety circuit, integrated directly in the transmission hydraulic circuit of all VAG vehicles. When necessary, a part of the gearbox is depressurised to prevent any transmission clutches from closing uncontrolled due to  excessive clutch pressure. This is feature is called the "Emergency Program" aka "Limp Mode"  or "Limp Mode Home".

When your Audi, Volkswagen, Seat or Skoda's  EPC light,  and or the Check engine light,  and or DPF (Diesel Particulate filter) light turns on, your car is likely to go into limp mode, if  it hasn't  already entered into Limp mode. Other than the illuminated light or lights in the instrument panel, and an engine that will not rev more than 2000 revs, neither exceed 30 kph, it gives you absolutely no explanation why it happened.  To make matters worse, there is no definitive list of what causes this elusive limp mode but I have tabulated some of them from personal experience. 

How to fix limp home mode

• Throttle Pedal Sensors (TPS), G79/G185
• Throttle body Position sensors, G187/G188 
• Throttle Valve Control Module, J338
• Engine Component Power Supply Relay, J757
• Intermittent Ignition Coils, N, N128, N158, N163
• Fuel Injectors N30, N31, N32, N33
• Transmission Control Module J217
• Waste-gate Actuator Valve, N75
• Knock Sensor, G61 
• Fuel pressure sensor G247 
• Fuel pressure regulator valve, N276 
• Automatic transmission electronic pressure control (EPC )   solenoid / stuck solenoids
• Transmission solenoid harness

Volkswagen Automatic Transmission Solenoid and Harness kit.

The only way to repair an EPC fault (Limp Mode) or for that matter any fault on any VAG vehicle, is to do a DLC scan to pull the Diagnostic Trouble Codes (DTC) to at least point you in the right direction. One of the most miserable Limp mode experiences ever is a Transmission Limp Mode. They range from a transmission that is low on fluid, to stuck in 2nd gear, to jumping out of gear, to noisy gears selection. But the worst is when  engine antifreeze water from the radiator enters through the corroded ATF cooler lines into the transmission, also allowing the ATF to leak  into the engine coolant, radiator and engine. 

Knowing the Germans, their just had to be a oil cooler for the automatic gearbox integrated somewhere into the radiator. Even though VW claim that ATF is a lifetime fluid", it is only a matter of time before it mixes with antifreeze and water. Anyway, this happens to  the all-in-one radiators  of Volkswagen Jettas, VW Golf 4, Passat B6, Audi A4 Quattro  and I suspect other VAG vehicle which I havn't personally experienced. It also happens to the Mercedes Benz C250, but it's  not an exclusive German car design flaw. It s also prevalent in the Nissan Pathfinder, Fords and Pontiac as well as several Asian vehicles.

Once the oil cooler lines spring a leak inside the plastic radiator, it messes-up the entire system by mixing the anti freeze water mixture with ATF. Yet with all the vehicle on-board electronics there is no visible sign that this cross flow happened nor any electronic detection or indication. Since oil is less dense than water, the gears in the transmission runs in water which causes the  metal gears to rust besides taking  the facings off the clutch plates. Beside the water shorts out the printed circuit board driving the solenoids on the valve body. This type of extensive damage can result in a very expensive transmission replacement if it isn't detected before the damage is done. 

Volkswagen  valve body

An easy way to identify this problem, is to check the ATF dipstick level often, which needs to be between the two notches marking min and max. Much more than that can indicate ATF floating on water. Also verify that the colour of the ATF is translucent red and not brown or black. Bi-annual ATF replacement, though expensive should almost guarantee a trouble free transmission. The logic behind an all-in-one radiator ATF cooler is to heat-up the ATF with the hot radiator water during cold conditions because oil tends to become thick and gel when very cold.  But is may be in your interest to replace your all-in-one ATF cooler with a separate / free standing oil cooler as used in the new cars if you live in a country where it never snows or never experience freezing cold weather.

Universal Aluminum  after market Automotive 13-Roll Transmission Oil Cooler

NEW GENERATION ALL ELECTRIC PHAETON LUXURY SEDAN

New Generation All Electric Phaeton Luxury Sedan

Volkswagen has been delaying the inevitable for way too long by fooling around with emission cheating devices in its EA 189 TDI - 2.0L and 3.0L Diesel Engines, and completely missed the window of opportunity enjoyed by its competitors. To the point that the EPA has placed a halt on all VW diesel engines destined for use in 2016 vehicles.  Meanwhile Toyota sales have topped VW sales for the month of November and outsold Volkswagen for 5th straight month. At this rate Toyota is likely to outsell VW for  December and very likely for the entire year of 2015. 

I'm certain this vexes Volkswagen greatly because Volkswagen has been blowing its own horn as the 'Group of the year for 2014' even though  they are no longer considered among the top fifty companies in Germany. In an attempt to regain its status and as a measure to contain the fallout of the Diesel emissions debacle, the newspapers and magazines have been inundated with Volkswagen Service offers flaunting slogans like.

"Volkswagen Service is proud to introduce Volkswagen Economy Packages".

"Nobody knows Volkswagen better than we do and  nobody's better equipped to service it."

"Let the people who built your car, service and repair your car". 

 "Volkswagen only uses Genuine Parts".

"You  get service of the highest international standard - 100% Volkswagen service".

"Your Volkswagen is Serviced by Volkswagen Certified  Technicians, highly trained and relentlessly dedicated".

The million dollar question is, "Is this enough to make a come back" or "Is it a matter of too little too late". The Diesel Gate Scandal  that cost Volkswagen tens of billions of dollars only caused an enormous surge in EV interest. Today EV prices compare very favourably with petrol and diesel equivalents and electric cars are no longer the preserve of the rich minority. They are now available to anybody who wants a reliable, cheap-to-run car because the days of spending $75 per week to fill up your polluting car will soon be over. 

Considering electric cars have no emissions, and their speed, performance and range have vastly improved. EV's carry no road tax levy and its running costs are as little as 4 cents per mile, a quarter of the average cost for petrol / diesel cars. The Toyota Prius is currently sold in more than 90 countries and its global cumulative sales have passed the  5.2 million units mark  in July 2015. This figure represents 65.4% of the 8 million hybrids sold worldwide by Toyota Motor Company since 1997. Toyota's sales figures for the first three quarters of 2015 stands at 21,210,000,000.00 JPY = 162,256,500.00 EUR or 176,255,100.00 USD.

Volkswagen is on the back foot for not embracing EV's sooner and is scrambling to get their New Generation All Electric Phaeton Luxury Sedan to market by 2017, which is destined to rival both Tesla and Mercedes Benz. The next big question is, "Can VW pull this off sucessfully"?

Initially when Volkswagen's launched their first-generation Phaeton luxury sedan, their objective  was  to prove that they are the world's innovation and engineering leader, and not Mercedes-Benz or Rolls Royce. But the $70,000+ Phaeton was a flop in  North America and was discontinued, yet  it  underpinned the hugely successful Bentley Continental and the Audi A8. From this one can easily see that the Phaeton was probably something very special hence it survived the chopping block,  as all  non essential / unnecessary projects were scrapped because of the ongoing diesel emissions scandal.

A rendered model of what the New Generation all electric Phaeton luxury sedan could look like.

Tesla Signature Series Model X with Tesla's Autopilot autonomous driving system.

VOLKSWAGEN GOES ELECTRIC

VOLKSWAGEN WAS DELAYING THE INEVITABLE

EV's (electric vehicles) has been around as long ago as the mid 1930's, but back then, they were called trolleybuses or  trams. As can be seen in the two images below, these EV's served as mainstream transport for the masses and believe it or not, are still in use in many places in Europe today. The technology though very old, is of long standing and proven, which is essentially a high voltage  electric motor that can deliver high horsepower at high RPM, connected via a gearbox to the drive train. Talking about trains, trains are in fact also EV's but with a slight difference. These EV's of days gone by, both trams and trains are attached to some sort of umbilical from which it received its electrical power to propel whereas modern EV's rely on portable battery power which until now hasn't been very efficient. 

But according to Elton Musk, CEO of  Tesla motor company, this isn't strictly true because they have an entire range of Tesla cars that can do as much as 265 miles (426 km) between battery recharges. He is also of the opinion that the maximum limit of what’s possible with diesel and gasoline has been reached and that the time has come to embrace a new generation of technology.

Trams in Alexandria Eqypt.

Trams in Vienna by Martin Otner

Frankly speaking,  I don't think its about the battery's inefficiencies but rather about the lack of facilities to charge your EV's battery when enroute or at your destination. But in the same breath I need to add that the charging problem is easily surmountable because a solar panel driven charging system (green technology) can easily be sold as an accessory with every EV and can be installed in your home garage. An overnight charge would give the average vehicle user sufficient power to commute virtually all day.

Admittedly, getting high efficiency from a high-voltage motor powered by a lithium-ion battery pack is not easy because there are many factors that effect efficiency, non of which I believe would have been too difficult for Volkswagen to solve. It just kinda seems that Volkswagen was delaying the inevitable even tough they've been flaunting their all-electric, minicar, e-up concept for the past number of years. Yet whilst still grappling  with the global fallout that originated from its diesel emissions scandal, VW recently reaffirmed the brand’s commitment to electrification. Sharing that they are working on a "standardized electric architecture" for all VW vehicles  with motors and flat battery design components that can fit in the various VW vehicle body shapes and vehicle types. 

Adding that VW is  also creating a new business segment called “New Volkswagen” to bundle modern development of digital features for Internet connected vehicles and other related mobility services. This announcement was  based on the  fact the  Silicon Valley firms like Apple Inc. and Alphabet Inc. are planning to make inroads into the automotive segment with software development and battery production. 

Vw even released a photo of its brand new all-electric concept car with an expected  driving range of 155–186 miles, scheduled to debut at the Consumer Electronics Show in Las Vegas in Jan of 2016. But the main surprise was the news that the next generation Phaeton super-luxury sedan will be an EV—only and not available in nether diesel or gasoline. Its going to have  a pure electric drive with long-distance capability, connectivity, and next-generation assistance systems as well as an emotional design.

VW AND AUDI EPC SOLENOID

VW AND AUDI EPC SOLENOID REPLACEMENT 

Its been four months since the accident that triggered both my VW Polo's airbags. Even though damage to the body was slight, my polo has been standing for all this time while repairs were effected. Now that everything is fixed and ready to take the Polo on the road once again, there appeared to be a huge problem. I couldn't select any gears whilst the engine idles because it grinds horribly but was able to select them when the engine is off. I have even selected a gear then turned the ignition, just to see it the clutch and pressure plate engages. After several attempts at grinding every gear, I came to the conclusion it may not be the gearbox that's at fault but perhaps the clutch that is not disengaging from the flywheel sufficiently.  So I started the engine and pumped the clutch for a several minutes. Thereafter it started selecting gears with difficulty and after several attempts it was back to normal. I took the Polo on the road and every thing was just great. 

02E  Automatic Transmission EPC Solenoid DSG  Gearbox  valve body   (Electronic Pressure Control) solenoid 

This so reminds of my friend Aron who also had or rather is still having a nasty transmission problems with his Jetta.  When he selects a gear, there is  loud thud coming from the transmission, then the  P, N, R, 1, 2, 3 light in the  instrument cluster flash red for a while then just stays on. In fact the light display is reversed, solid red back ground with whiteout text.  His car is fitted with DSG transmission. Direct-Shift Gearbox (DSG), Multitronic DSG / CVT Transmission  repairs can be and are invariably quite expensive and this problem looked and sounded very expensive. So to save money, he decided to repair it himself.  After watching what he had to do, I realized that a bad transmission is definitely not a DIY project, unless you have the mechanical and electronic expertise and the necessary specialized equipment. 

A 02E transmission scan came up with the following data:- 

 Address 02: Auto Trans Labels: 09G-927-750.LBL
Control Module Part Number: 09G 927 750 HJ HW: 09G 927 750 CJ
Component and/or Version: AQ 250 6F 1068
Software Coding: 0000072
Work Shop Code: WSC 31414 000 00000
4 Faults Found:

17104 - Transmission Output Speed Sensor (G195): Circuit Malfunction
P0720 - 012 - Electrical Fault in Circuit - MIL ON
Freeze Frame:
Fault Status: 10101100
Fault Priority: 2
Fault Frequency: 1
Reset counter: 44
Mileage: 104552 km
Time Indication: 0
Date: 2010.10.19
Time: 16:39:08

17099 - Transmission Input Speed Sensor (G182): Circuit Malfunction
P0715 - 012 - Electrical Fault in Circuit - MIL ON
Freeze Frame:
Fault Status: 10101100
Fault Priority: 2
Fault Frequency: 1
Reset counter: 39
Mileage: 41353 km
Time Indication: 0
Date: 2015.08.08
Time: 00:00:00

17094 - Transmission Fluid Temp.Sensor (G93), Circuit Malfunction
P0710 - 010 - Open or Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00101010
Fault Priority: 2
Fault Frequency: 1
Reset counter: 184
Mileage: 41353 km
Time Indication: 0
Date: 2015.08.08
Time: 00:00:00

01680 - ABS Wheel Speed Signal; Front Right
013 - Check DTC Memory
Freeze Frame:
 Fault Status: 00101101
Fault Priority: 2
 Fault Frequency: 7
Reset counter: 201
Mileage: 41353 km
Time Indication: 0
Date: 2015.08.08
Time: 00:00:00

The transmission gets  a speed signal from the front right side wheel which is needed by the TCM to determine the speed of the car and when it should change gears hence there is an ABS fault listed above. After stripping the valve body, he found that the transmission oil looked like there was water in it, a sort of milky grey instead of reddish translucent. It turned out that the previous owner never bothered to replace the transmission oil at all. There were iron fillings attached to the magnets in the sump and some black plastic bits from the solenoid plugs could be seen in the oil, liquidized by the gears.  This most likely caused solenoid EPC (electronic pressure control) solenoid to seize, preventing it from moving when pulsed because it caked-up around the plunger.  In fact the entire loom was so brittle when  it was unplugged that it just disintegrated into crumbs.  Considering that the engine is attached to the transmission, both of which produce tremendous heat which virtually "cooks" the transmission oil at 40 degrees C. Its no wonder the transmission harness  is overcooked hard and brittle because it lies in this hot oil. It's also very surprising that VAG cars with DSG transmissions aren't more trouble some than they already are, because the electronic mechatronic unit sits inside the gearbox. As bad luck would have it, Aron's Jetta's mechatronic device was fried and needed to be replaced along with the internal harness.  No electronic component other than "military spec electronic components" was designed to withstand of survive such huge amount of heat.  

Anyway, the EPC (Electronic Pressure Control) solenoid was replaced after the valve body tunnels was cleaned with a rifle cleaning wire brush and reassembled. Two more rubber seals on two other solenoids were also replaced and as mentioned earlier, the mechatronic unit and the internal harness.

LIMP MODE Q&A

LIMP HOME MODE

When I initially bought my VW Polo 2.0L she was a thrill to drive. Her speed was instant, cornering was really good and road holding never better. She was a joy to drive, very unlike my VW Golf II, but then I started getting car troubles,  which were many and varied. My first encounter with VW agents was a disaster. After they "repaired" my EPC fault they charged me a ridiculous sum of money, only to experience the same EPC problem the following day.  After speaking to several of their mechanics, who collectively were unable to fix my car, I came to realize  that I was either far more knowledgeable about automotive electronics than all of them put together, or they knew very little about electronics.  This just put me off the agents completely and when I took my Polo to independent mechanical workshops,  I found the same to be true. I still remember how lost I felt when my VW Polo went into limp mode the first time and the second and the third and the fourth. I felt lost, stuck on the freeway, late for meetings, frustrated and miserable because I couldn't repair her like I did the VW Golf II due to the fact that the Polo had OBD-II. I  thought my VW Polo to be unreliable, there was a point that I feared driver her at night, and later started to hate  even diving the Polo.  I was literally on the verge of setting her alight. But them I decided to buy a Ross Tech cable and downloaded their VCDS and my Polo is a joy to  drive once again. The rest of this blog is devoted to 10 vehicles owners who have experiences similar trouble with their VAG vehicles ranging from Drive by wire problems, to EPC trouble, to DTC trouble Codes to CAN-Bus-issues to name but a few. 

DRIVE BY WIRE
Steve sent this:- Had the problem of no power, tried the technique described in your blog (disconnect battery, wait, reconnect, turn ignition key, wait, turn off, turn engine on, wait, press throttle...) - and it worked beautifully. Many thanks for your help, very much appreciated - particularly as you've probably save me many pounds. 

QUESTION? - DRIVE BY WIRE
Anonymous sent this:- I have a '07 Polo 1.4 16v BUD. I don't have any lights on the dash, but the engine seems really weak through mid revs and is using a bit too much fuel. When I hook up my OBDII there are no faults recorded but when I view the throttle position in real time it doesn't seem to open in a linear manner. As I press the pedal on the road, the throttle valve seems to open slower than the position of  the pedal. eg; 50% pedal = 30% throttle position, 80% pedal = 35% throttle, 95% pedal = 40% throttle, 100% Pedal = 100% throttle. As you can see WOT does give WOT at the throttle body, but I don't generally drive with my foot planted on the floor. I am confused why it does this as you would expect the throttle body to open the same amount as the pedal, could it need alignment? I am loathed to take it to the VW dealer for fault diagno$i$ so if anyone has any ideas????  Thanks 

ANSWER!
On drive by wire model vehicles the throttle doesn't open like legacy cable throttles because its electronically controlled. 

DRIVE BY WIRE
Durell  Dunn  left this:- I am currently experiencing the same problem with my 2003 polo,1.4. The car goes into limp mode and on some occasions switches off in traffic, hectic ! I will use your method. Thank you for saving me from going to a VW dealership, all I can do at this stage is do and hope 

DRIVE BY WIRE
Loci sent this:- Hi. I have a problem with my Volkswagen Polo 1.4 Tdi. It seems to have a good start but after I drive for around 35 minutes it loses the power so I could not pass 2000 giro. Thank you for your suggestions.

QUESTION? - DRIVE BY WIRE 
Anonymous asked:- My car is a polo 1.4 2012 model. When I start the car the EPC light switch on then I put gear to move the car but it limbs then I switch it off then start it again then the EPC light does not switch on then off I go... What could be wrong? 

ANSWER!
The trouble can be one of many things, among which are your accelerator pedal, throttle body, knock sensor, Fuel pump pressure, even a loose fuel cap. You need to check through each systematically but for that you at least need a scan of your vehicle.

ENGINE LIGHT COMES ON
Lee Kyprian left this:- Everyone who has ever owned a car has experienced the confusion and even panic which can arrive when your check engine light suddenly comes on.

QUESTION? VW ELECTRONIC POWER CONTROL
Abror Isoqov sent this:- Hello. My car is VW Golf 1.6 16v and I have a problem with acceleration it has no enough power. It accelerates very slow and at 5th gear it can get max 130 km/h. At neutral position when engine gets about 5000 rpm the EPC light comes on. After restarting the engine it goes off. Tester didn't determine any trouble codes. What can cause for this problem. I went about 7-8 auto services but any of them could help. But I didn't go to VW dealer because it will be very expensive. last time they charged me $125 just for diagnostic.  Please help me with this issue.   

ANSWER!
What you explaining is limp mode and everything else seems very odd. Because by the time the EPC light does go on, a DTC is already set which any scan tool should be able to retrieve. Unless there is a problem with you DLC wiring, so that communication between vehicle and scan tool is erroneous.

VW ERROR CODES
Steve Cain sent this:- Hi, vw polo 1.4tdi 2003, AMF engine code,  problem is that when driving at any speed, car looses all power, engine stuck on 1200 rpm, throttle pedal no response, glow plug heating light flashes, switch off & switch back on straight away, car drives normally, no warning lights. Can you shed any light on this problem, (driving my wife mad). Thanks, Steve 

ANSWER!
I have covered this problem quite substantially in previous blogs and it in your interest to ready through them.

WON'T REV
Anonymous sent this:- My VW Jetta 2002 1.8t stopped me on the highway and it refused to rev and the mechanic says it is the brain box. I don't understand is he correct?

ANSWER!
Yes he is correct, problem lies in the ECM circuit but not necessarily the ECM itself. Dude you need to get your car scanned to get a better idea of  the actual problem.

CAN-BUS
Hi! I read your blogs and saw writings from you  about the CAN bus protocol. I have a problem to understand something on my cars OBD connector and the CAN bus line. Can you please help me maybe? Can we talk about? When I connect my 2 channel  DSO to the OBD connector pin 6 and pin 14 ( CAN-H and L ) and pin 5 (GND) on my VW Polo 1.4D year 2003 I got this signal what I posted right now. But, when I do the same think on my Renault Clio 1.5DCI year 2003 I got the right CAN signal.  

ANSWER! 
The likely hood is that your VW Polo isn't CAN compliant because its still a 2003 and used KWP-1281 and KWP-2000 protocols.  All VW's after 2008 is fully CAN compliant.

EPC Q & A CONTINUED

EPC Q & A CONTINUED

It appears that more and more VAG drivers are experiencing Limp Mode with their VW, Audi , SKODA and SEAT vehicles and it appears that service agents are not as competent as expected. This urged me to present 3 more limp mode cases on a VW Beetle, VW Golf and a Golf TDI for the benefit of those with similar vehicles.

Question?

Hello my name is Mariiam Lopez. I have a 2002 VW beetle. I had been having problems with my car for more than a year. First started with the EPC LIGHT on, I had it on for a few weeks and it came and went, but then my car started to lose power while driving. I had to park and turn it off. I would wait a few minutes and then I started it again and the light went off . But then the EPC light stayed on and the speed didn't go up 10 miles (limp mode). I went to a mechanic and he said it was the throttle body. I had it changed. Two days the EPC LIGHT got on again. I took it again to another mechanic and he said it was the accelerator sensor. I change it and I even got the pedal. Next week got the EPC LIGHT on. It was driving regularly until it didn't want to turn on. I let my car rest for more than two months. I stared using it for a few weeks now and the EPC LIGHT goes on and off when I turn off. Now while driving in the freeway my car lose power and I have to park and let it rest for a few minutes and it drives fine but after a few minutes EPC LIGHT turns on. Now my car turns off in the middle on the freeway and all the lights on the dashboard are on. I park and turn on again but I have to accelerate in order to make my car work. Also the red oil light goes on and beeps when EPC light is on. My car has the same radio. Thanks

Answer!

Hola Mariam como estas? I so sorry to hear that you've had so much trouble with your VW Beetle and for such a long period of time. I can relate to what you are going through every time you need to go somewhere, especially at night when you have to drive a car that is completely unreliable. Considering that two mechanics, both of whom guessed that your throttle body and your accelerator sensors were faulty and that both parts were  replaced and your Beetle is still faulty, makes you saint with the patience of biblical Job. But your mechanics are not alone, so many VW service agents replace parts on Beetles and other VAG vehicles on a regular basis which often doesn't fix the problem, making car owners constantly despondent with VW and their "technical personel". At this point in time  I would be very hesitant to suggest that you replace any component without a diagnostic scan of your Beetle. It would have been great if you can get a copy of your Beetle's scan from one of your mechanics and upload it, so that I can  properly analyse it. Mind you, the data in group 60 - group 66 would  really be helpful to determine whether or not the adaptation was successful.  The EPC light problem can be caused by some many things and in your case its not your radio. So I suggest you check the fluid levels of your oil and coolant and make sure the coolant isn't leaking from reservoir bottle onto the wiring harness, if it does, the instrument panel is bound to malfunction. Also check that your fuel cap seals properly and check the vacuum hoses from the brake booster to the secondary air inlet valve and the hose to the combi valve. If this doesn't solve your problem, read through some of my other blog pages to get a better idea of what must be checked. I don't wish to scare you but Beetles especially MY2000 are well know for electrical problems and catching alight with the flames originating from underneath the firewall,  burning its way up the wiring harness, melting the fuse block on top of battery. So do take care.

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Question?

Hello my friend. I'm Charles Gunn and I have a VW golf mkv fsi 1.4 2005, which I bought in December of 2007. Since I bought her, she's been going into limp mode when I least expect her to, and have had this problem for the past three years. In my endeavours to fix it, I've tried so many garages, non of whom  could help. Worst of all a VW dealer charged me well over £1200, for replacing the wrong components, making me go back and forth to them, yet they never sorted out the problem. Furious... My VW golf goes into limp mode regardless of weather conditions and especially on long drives and on the motorways whenever I exceed 100kph. I found switching off the engine and letting it cool before staring helped but this was temporary because when it becomes hot, limp mode returnes. She frequently lost power when going up hill or on an incline to a bridge. I've done lots of internet  research and tried most forums but no luck. Thus far I've replaced the NOx sensor, MAF sensor, four coil packs and a fuel rail pressure sensor and an air filter. I spent over £1500 and still have a limp mode problem. Can you please help me? The fault that showed up on the scan is; 

1 Fault Found 
16575 - Fuel Pressure Sensor (G247): Implausible Signal 
P0191 - 008 - Implausible Signal - Intermittent 
Readiness: 0000 0000

Answer!

Hi Charley, I must commend you for your perseverance and for your gusto to kick limp mode's ass. Three years of limp mode is probably more than most people can bear. Anyway I see that you replaced a NOx sensor even though your Readiness is 0000 0000. A faulty NOx sensor would have interfered with your short term fuel trim, which would have resulted in a 0010 0000 readiness. A faulty MAF or air filter would also  have also interfered with your readiness which would have resulted in 0001 1000 reading. I'm so sorry to say that you replaced these items, because according to your readiness monitors they are not he cause of your troubles. The coils you replaced can cause limp mode but would also causes the engine to vibrate and idle poorly which would have also given you a P0300 (misfire) error code, so I think they were also replaced unnecessarily. The fact that you replaced the fuel rail pressure sensor says that your were definitely on the right track as pointed out by theP0191 fault, which may have been faulty hence sending intermittent signals to the ECU. However I am more inclined to think that your submersible fuel pump inside the tank is the culprit since it is responsible for creating the fuel pressure, which  is absolutely necessary to drive the injectors. But before you replace the pump, monitor the voltage supply to the pump since corrosion on the fuse in the fuse box that supplies the fuel pump voltage could cause a very similar symptoms.

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Question?

Hi, I need your advice  and please go easy on me because I'm a woman, who  knows very little about cars.  I have a Vw Golf GT TDI 2.0 with 81000 miles on the clock, which I bought about a month ago and it goes into limp home mode, whenever I get to about 70 mph and 3000rpm's but it comes right  when the engine is turned off and back on again. The local garage  ran a dianostics check and they suggested that I either put some diesel cleaner into my tank or use cleaner diesel as they think it's the turbo sensors that  gets clogged-up with soot! I've done some internet research and forums suggested I check the MAF.  So yesterday i drove the Golf untill it went into limp mode, then I switched off the engine and unplugged the MAF.  I could feel that the turbo wasn't working, not as responsive as it usually is. Anyway I drove upto 75 mph, when limp mode usually kicks in. Nothing happened and I increased my speed to 85mph and limp mode still didnt make an appearance. I stopped the Golf, switched off the engine  plugged MAF back in and sure enough limp mode kicked in at 75mph, do you think I need to change the MAF or could it be something else causing the problem?

Answer!

Hi there. It really would have been great if you had a diagnostic scan from which to work but since you don't have one, analysis is bound to be difficult and probably inaccurate. A MAF sensor can cause a limp mode home fault but it doesn't not mean it is faulty in your case. By disconnecting the MAF sensor the OBD System Component Monitor would immediately determine that the  mass airflow  sensor circuit voltage is outside an acceptable range. Thus One of two things could happen:-

1. The ECU will prevent the car from starting.
2. The engine will start but may trigger the malfunction indication lamp (MIL) and the car would also smoke profusely. Since the ECU cannot achieve the required stoichiometric ratio, it will trigger a DTC P1101 in memory. If the ECU supports "failure mode effects management" (FMEM) it will  default to a ‘safe’ mass airflow value, allowing the the vehicle to be driven to workshop for repair. Somehow I think you may not have unplugged the MAF but it is worth your while cleaning the MAF but be careful not to damage the wire inside.  Since  your car is Diesel I somehow doubt that is would be the MAF .

Question?

Nazeem Sterris. Hi.I have a polo 1.4 16v bby.problem is epc light stays on. It starts well.revs up well but has a slight miss fire when idling.after couple of minutes of idling it goes into a limp mode where revs go up to 1500rpm and pedal don't work. Pls help

Answer?

Hi Nazeeem. The slight miss you are describing is most likely the cause of your EPC problem. Sorry, I cannot pinpoint the problem for you because  you don't have a diagnostic scan attached, I'm guessing that the miss could be associated with your Ignition Coils, your Fuel Injectors,  or your Throttle Body, or your Fuel Pressure Regulator Valve or even your Wastegate Bypass Regulator Valve. You need to work through them systematically but first check that your fuel cap seals because if it doesnt, the EVAP pressure cannot stabilize  and can also trigger the EPC circuit.  

LIMP MODE

LIMP MODE HOME / VW LIMP MODE

What is "limp mode", has been "The Question" of  2013-2014.  Limp mode is a design feature of all drive by wire systems. Vag cars fitted with ME 7.0 or newer are all fitted with electronic drive-by-wire systems in place the fast aging and outmoded cable throttle system.  Bosch ME 7.5 ECU is a very complicated system, which is torque based and makes decision based on input and feedback from all sensors needed to perform the stoichiometric calculations for optimum engine performance and torque. Failure of any of these components triggers its built-in the safety feature "limp mode" and lights up the EPC warning light. Unlike cable systems that can fray and get  stuck at high revs or high speed which often result in accidents,  "limp mode" deactivated torque and limits the revs to 1500 rpm yet allows the car to limp home safely. Many are asking, how to fix "limp mode"? The following cases are all different yet had the same symptoms - limp mode turning on the EPC warning light. The first is a Jetta, the second a Polo, the third a Seat Ibiza and the fourth a Skoda Fabia. See also  VW Polo highline, vw volkswagen limp mode,   limp home mode and  Audi limp mode.

FIRST CASE / VW LIMP MODE

Lately I've been having some issues with my Jetta 2.0T. She just suddenly went into "limp mode" or "safe mode" and it happened thrice during this week, resulting in total loss of power. I'm at my tether end, I have no idea what to do or how to rectify the situation. The first two times she went into "limp mode" the EPC warning light did not come on, however on the third occasion it came on and now stays on and  hasn't gone off since.  Initially I thought it was because the pump jockey threw-in LRP instead of unleaded fuel  but I have since rectified the situation and its not that.  I've run Vag-com diagnostics twice, which revealed the following data. I need help to repair this problem else I would have to take it to the service agents. Just the thought of a huge repair bill kept me from going there in the first place.

(First scan)
Control Module Part Number: 1K0 907 115 B
Component Version: 2.0l R4/4V TFSI 00 0010
1 Fault Found:
000818 - Knock Sensor 2 (G66): Signal too Low
P0332 - 002 - Lower Limit Exceeded - Intermittent

Freeze Frame:
Fault Status: 00100010
Fault Priority: 0
Fault Frequency: 2
Mileage: 18745 km
Time Indication: 0
Date: 2015.01.12
Time: 14:41:21

Freeze Frame:
RPM: 2555 /min
Load: 86.1 %
Speed: 52.0 km/h
Temperature: 77.0°C
Temperature: 39.0°C
Absolute Pres.: 1001.0 mbar
Voltage: 14.323 V
Readiness: 0000 0000

(second scan)
Address 01: Engine
Part No SW: 1K0 907 115 B HW: 1K0 907 115 B
Component: 2.0l R4/4V TFSI 00 0010

1 Fault Found:
000818 - Knock Sensor 2 (G66): Signal too Low
P0332 - 002 - Lower Limit Exceeded - Intermittent

Freeze Frame:
Fault Status: 10100010
Fault Priority: 0
Fault Frequency: 2
Mileage: 18992 km
Time Indication: 0
Date: 2015.01.15
Time: 12:05:11

Freeze Frame:
RPM: 2444 /min
Load: 57.1 %
Speed: 61.0 km/h
Temperature: 89.0°C
Temperature: 45.0°C
Absolute Pres.: 989.0 mbar
Voltage: 12.066 V
Readiness: 0000 0000

EXPLANATION
Our fellow VW owner is concerned with the different results of his two scans. So first and foremost let me assure him that there is nothing to worry about because the Readiness passes with flying colour. Readiness is the operational status of  the 8 emission functions, viz  the (1st nought) Exhaust Gas Recirculation - EGR, (2nd nought) Oxygen Sensor Heater, (3rd nought) Oxygen Sensor, (4th nought) Air Conditioning, (5th nought) Secondary Air Injection System, (6th nought) Evaporative Emissions System, (7th nought) Catalyst Heating and  (8th nought) Three Way Catalyst.  However, not all vehicles are fitted with all 8 system. If the system is absent, the report default to a 0 but  a 1 signifies a fault in the respective system. The RPM, load, Speed and Temperature above, are all relative to how long the engine has been running, the gradient of the road etc. The Absolute Pres of 989.0 mbar is lower in scan two  than the Absolute Pres. of 1001.0 mbar of scan one  because the battery is lower. The optimum battery voltage is 14.4V. Anyway, to get back to the "limp mode" issue at hand.  I am almost certain the cause of "limp mode" in this case is the Knock Sensor 2 (G66) because of Signal too Low - lower than expected by the ECU.  The mere fact that the ECU reports a low signal implies that the wiring from the knock sensor to the ECU is intact and that the actual fault could be the knock sensor or the ECU itself . It is highly unlikely that the ECU is at fault because they are fairly robust, which leaves us with the knock sensor. Knock Sensors are torqued to the engine block for flush contact so that it would pick up the maximum amount of vibration. Should the bolt securing the Knock Sensor come loose, the knock sensor would send a lower signal than expected. See previous blog  Knock Sensor issue. Since the ECU cannot protect the engine in the absence of knock sensor 2 it decided to enter into "limp mode" to safeguard the engine from possible damage it a knock developed or vibrations exceeded the prescribed limit.

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SECOND CASE  / VW LIMP MODE

I have a 9N - VW Polo and my car's EPC warning light comes on when I rapidly accelerate when driving at slow speeds or when accelerating rapidly while driving a steady speed. When the EPC warning light comes on, the car goes into "limp mode" at that very moment then he check engine light comes on.  I’ve scanned the ECU with VAG-COM  and after spending hours under the bonnet looking for a possible cause, I still haven't found  anything and need help or any suggestions so I can fix this problem.

Address 01: Engine
Part No: 036 906 034 FJ
Component: MARELLI 4MV 4830
3 Faults Found:

17961 - Barometric / Manifold Pressure Signals
P1553 - 35-10 - Implausible Correlation - Intermittent

17912 - Intake Air System
P1504 - 35-10 - Leak Detected - Intermittent

17550 - Load Calculation Cross Check
P1142 - 35-10 - Lower Limit Exceeded - Intermittent

Readiness: 0000 0101

EXPLANATION

The fact that the Readiness failed (see explanation above) more than explains why you are having car trouble. Since the 6th nought is a 1, it says that your  Evaporative Emissions System (EVAP) is faulty. The 8th nought is also a 1, which says that your Three Way Catalyst is at faulty. However, in your case it appears that hardware upstream of the catalytic converter is causing  the readiness to fail. The problems are associated with  Leaks Detected in the Mass Air Flow (MAF) / Intake Air System / Barometric / EVAP system . Since the incorrect amount of air needed  for stoichiometric calculations is inadequate, the fuel is not completely burnup and as a result the catalytic converter detects unburnt fuel and flags an error. The units themselves may not be faulty but rather the wiring and connectors of these units or cracks or cuts in the rubber hoses.  Repairing these should take  priority  because OBD-II is designed to shut the car down if it fails readiness and there therefore the minimum emission standards. Since the fuel is under pressure and the rubber hoses could be leaking fuel, safe mode (limp mode) is initialised.

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THIRD CASE  / VW LIMP MODE

What is limp mode? My 6L-Seat Ibiza can idle but not rev, I think it has gone into limp mode, please help before I set this cas alight. Please explain what is limp mode? And how to fix limp mode. Here is the VAG-COM scan of modules with faults,

Address 01 ----------------------------------------------
Controller: 038 906 019 NF
Component: 1,9l R4 EDC 0000SG 5839

2 Faults Found:
18043 - Powertrain Data Bus: Missing Message from A/C Controller
P1635 - 35-10 - - - Intermittent

18045 - Powertrain Data Bus: Missing Message from Electronic Load Controller
P1637 - 35-10 - - - Intermittent

Readiness: N/A

Address 03 ----------------------------------------------
Controller: 6Q0 907 379 S
Component: MABS 8.0 front H03 0001
Coding: 0000008
Shop #: WSC 06441
Note: Excessive Comm Errors

Address 08 ----------------------------------------------
Controller:
Note: Excessive Comm Errors

EXPLANATION
For an explanation of what limp mode is, read the above. The two engine faults signify there could be a problem with the Data bus Wiring since neither the Electronic Load Controller nor the A/C Controller can send and receive messages. Coupled to the fact that Address 3 - ABS braking system  and Address 8 -Auto HVAC both have Excessive Comm Errors, further verifies trouble with the  Data bus. However it is more likely Fuses and /or Connector(s) from / to Central Electronics Control and the Gateway controller. The fact that the ECU cannot coordinate torque and braking it was best to shut the systems down and enter into safe mode (limp mode) since malfunction of these important systems may lead to an accident and for the very least make for a poor driving experience.

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FOURTH CASE  / VW LIMP MODE

I have a Skoda Fabia and I think there is problems with the butterfly of my throttle body or perhaps it is dirty because the car goes into "limp mode" continually.  I have given up on kickdown because  it is getting dangerous because whenever I want to overtake, my car goes into limp mode.   I would appreciate your commentary and your recommendations because  "limp mode" frustrates me and I curse all the time. Do you think the sensors are causing all my problems? Here is my Vag-com scan.

Address 01: ----------------------------------------------
Engine
Part No: 036 906 034 BL
Component:  MARELLI 4LV       3699
Coding: 00071
 
No fault code found.
Readiness: 1110 0101

Address 08: ----------------------------------------------
Auto HVAC      
Part No: 6Y0 820 045
Component: Klimaanlage        X0760

1 Fault Found:
00818 - Sensor for Evaporator Outlet Temperature (G263)
30-00 - Open or Short to Plus

Address 09: ----------------------------------------------

Cent. Elect.  
Part No: 6Q1 937 049
Component: BORDNETZ-SG.1S30

3 Faults Found:
00906 - Horn (H1)
28-10 - Short to Plus - Intermittent

00778 - Steering Angle Sensor (G85)
49-00 - No Communications

01324 - Control Module for All Wheel Drive (J492)
49-00 - No Communications

Address 15: ----------------------------------------------
Airbags    
Part No: 1C0 909 601 C
Component: 02 AIRBAG VW51 01
 
1 Fault Found:
00532 - Supply Voltage B+
07-10 - Signal too Low - Intermittent

Address 19: ----------------------------------------------
CAN Gateway
Part No: 6N0 909 901
Component: Gateway K<->CAN 1S30
 
2 Faults Found:
00778 - Steering Angle Sensor (G85)
49-00 - No Communications

01324 - Control Module for All Wheel Drive (J492)
49-00 - No Communications

Address 44: ----------------------------------------------
Steering Assist  
Control Module Part Number: 6Q0 423 156 AB
Component and/or Version: LenkhilfeTRW        V270
Software Coding: 10140
1 Fault Found:

00816 - Power Steering Sensor (G250)
30-10 - Open or Short to Plus - Intermittent

EXPLANATION
This Skoda Fabia seems to have enough problems for half a dozen cars. Once again we need to look at Readiness first because it is quite evident that there more 1's than 0's. That tells us there are problems  in the (1st nought) Exhaust Gas Recirculation - EGR, (2nd nought) Oxygen Sensor Heater, (3rd nought) Oxygen Sensor,   (6th nought) Evaporative Emissions System  and  (8th nought) Three Way Catalyst. This is reason enough for the car to go into limp mode. But since it also has issues with its  Steering Angle Sensor (G85)
and the Control Module for All Wheel Drive (J492) there is even more reason to shut the important systemes down and do into safe mode (limp mode). There are also several electrical issues with open circuits and short circuits which would most likely be wiring harness related. But the most striking thing is the  Low - Intermittent  Supply Voltage B+ which implies the battery terminal is loose. Intermittent supply voltage  resets all modules all the time and can lead to spurious DTC.

WIRING HARNESS ISSUES

AUDI ON A ROLLBACK

As I've mentioned in my previous blog, not only Volkswagen  vehicles but every new vehicle's wiring harnesses have undergone a huge technological evolution since 1984. So much so that  30 years later the average wiring harnesses has become extremely complex because the number of terminals have progressively increased from a typical 200 terminals in a 1994 vehicle to as many as 1,400 terminals, if not more in the very latest models. It therefore stands to reason that with so many terminals or connections, each and everyone of them are subject to corrosion, high resistive contact, poor contact, intermittent and implausible contact  and at times no contact.  The amount of copper wire used in older cars have also decreased substantially, from as much as 4 kilometers in length to about 1 kilometer. That's equates to a 75% saving on the wiring harness.  However with all the new technology and control modules and data buses, the cost of the wiring harness  cost equates to a quarter of the cost of the entire car. 

VW Polo Wiring Harness

As can be see in the image below, another VAG car sucummbed to hi-technology and desperately needs the service centre because it went into "Limp Mode".  It's most likely an electrical fault has caused this but that's just speculation on my part. However, since more than 50% of all warranty repairs are caused by electrical malfunctions, and approximately 30 percent of all tow-ins, are due to problems associated with the wiring harness, it can be therefore be said that 80% of all troubles experienced by car owners today are due to electrical faults.  Can we then also say that these fault are constantly recurring  because the manufacturer has overlooked the fact that 1400 contacts will invariably be influenced by  bumpy roads, shaking and hoping and flexing, subject to moisture and heat and dust and dirt? Desktop computers also have several hundred contacts but the difference between household computers and cars is that computers stay in a fixed place and doesn't get knocked about and shake on bumpy roads nor subjected to extreme heat and cold and moisture. Wouldnt it be fair to say that any car with electrical problems caused by the wiring harness should be repaired by the manufacturer under warranty and if not, these cars should be recalled. Anyway,  here is the Audi scan for your perusal.

Audi on a roll back with immobilizer issues

Chassis Type: 8E - Audi A4
Scan: 01 02 03 08 09 0F 11 15 16 17 18 36 37 45 46 55 56 57 65 67 69 75 76 77
-------------------------------------------------------------------------------

Address 01: Engine Labels:
Part No: 8E0 906 018 B
Component: 1.8L R4/5VT 0004
Coding: 11701
Shop #: WSC 14385

7 Faults Found
17978 - Engine Start Blocked by Immobilizer
P1570 - 35-10 - - Intermittent
17698 - Coolant Temp Sensor at Radiator Outlet (G83)
P1290 - 35-10 - Signal too Small - Intermittent
00527 - Intake Manifold Temperature Sensor (G72)
30-10 - Open or Short to Plus - Intermittent
17536 - Fuel Trim; Bank 1 (Mult)
P1128 - 35-00 - System too Lean
18058 - Powertrain Data Bus
P1650 - 35-10 - Missing Message from Instrument Cluster - Intermittent
18043 - Powertrain Data Bus
P1635 - 35-10 - Missing Message from A/C Controller - Intermittent
16712 - Knock Sensor 1 (G61)
P0328 - 35-10 - Signal too High - Intermittent
Readiness: N/A


Address 03: ----------------------------------------------------------------------
ABS Brakes
Part No: 8E0 614 517 A
Component: ABS/ESP allrad 1326
Coding: 04275
Shop #: WSC 60690

1 Fault Found
01317 - Control Module in Instrument Cluster (J285)
49-10 - No Communications - Intermittent


Address 08: ----------------------------------------------------------------------
Auto HVAC

Part No: 8E0 820 043
Component: A4 Klimaautomat 0711
Coding: 00000
Shop #: WSC 24576

4 Faults Found
01317 - Control Module in Instrument Cluster (J285)
49-10 - No Communications - Intermittent
00716 - Air recirculation Flap Positioning Motor (V113)
41-00 - Blocked or No Voltage
00474 - Control Module for Immobilizer
49-00 - No Communications
00474 - Control Module for Immobilizer
27-10 - Implausible Signal - Intermittent


Address 09: ----------------------------------------------------------------------
Cent. Elect.
Part No: 8E0 907 279 A
Component: int. Lastmodul RDW 1010
Coding: 00011
Shop #: WSC 63351

4 Faults Found
01317 - Control Module in Instrument Cluster (J285)
49-10 - No Communications - Intermittent
00474 - Control Module for Immobilizer
49-00 - No Communications
01317 - Control Module in Instrument Cluster (J285)
79-10 - Please Check Fault Codes - Intermittent
01312 - Powertrain Data Bus
49-10 - No Communications - Intermittent


Address 15: ----------------------------------------------------------------------
Airbags
Part No: 8E0 959 655
Component: Airbag 8.4E 3001
Coding: 0011702
Shop #: WSC 63351 000 00000

No fault code found.


Address 16: ----------------------------------------------------------------------
Steering wheel

Part No: 8E0 953 549 F
Component: Lenks?lenmodul 0304
Coding: 00001
Shop #: WSC 63351


2 Faults Found
00474 - Control Module for Immobilizer
49-00 - No Communications
01317 - Control Module in Instrument Cluster (J285)
49-10 - No Communications - Intermittent


Address 17: ----------------------------------------------------------------------
Instruments
Part No: 8E0 920 900 HX
Component: KOMBI+WEGFAHRS. RB4 D27
Coding: 00142
Shop #: WSC 19411

2 Faults Found
01176 - Key
07-10 - Signal too Low - Intermittent
65535 - Internal Control Module Memory Error
00-00 - -


Address 45: ----------------------------------------------------------------------
Inter. Monitor

Part No: 8E0 951 177
Component: Innenraumueberw. 0504
Coding: 00001
Shop #: WSC 00000

No fault code found.

Audi on a rollback on the way to the clinic.

So by the looks of it, with so many error codes,  it does seem like the wiring harness could be faulty because the control module lost communications with the Instrument cluster and when this happened the checksum no longer tallied, so the immobilizer inhibited starting. But considering that the key signal was low or intermittent, it could even be that the CR1220 lithium battery in the key fob died hence could not deactivate the immobilizer. It's just so scary that your relatively new and supposedly reliable VAG vehicle could act up at any time on a lonely road and leave your stranded, so make sure you have a tow-inn agent on speed dial.


Feel free to upload your VW, SKODA, SEAT & AUDI scans.