Limp Mode Scan codes

LIMP MODE

Limp mode has hit car owners like a pandemic, a pandemic that was pre-planned by the automotive industry, knowing full well that most car owners would be at a loss to repair it themselves and that it was  going to be a source of steady profit, a bonanza, a money spinner, a cash cow, a golden goose for them.

Virtually every car owner have experienced the wrath of Limp mode at some time or the other and are often helpless when it happens. Those of you who haven't had the displeasure of encountering Limp mod surely will, its just a matter of time - virtually guaranteed.

STANDARD FEATURE

Limp mode is a standard feature programmed into all post-1996 vehicles to protect their engines and driver / passenger when something goes awry with its EPC system, steering or braking system, etc.  The ever-aware sensing software will activate this feature when it detects abnormal readings from sensors, or compromised mechanical part operations that could potentially cause damage to the vehicle or harm to its occupants.

Every time when Limp mode is triggered the ECU will store a DTC in its non-volatile memory for later retrieval. And since Limp mode can be caused by any of several different engine components, the only way to track down the Limp mode problem is by way of a OBD-II scan tool. Scan tools may be considered the vaccines against this Limp mode pandemic, implying only those who have one will be able to fix their own cars.

ON BOARD DIAGNOSTICS

OBD-II (on-board diagnostics ver2) gave rise to a scan tool market and these scan tools comes in several makes and models, with capabilities ranging from the most basic to the most intricate costing from as little as a few bucks to tens of thousands. Most of the low end scan tools are VW compatible though some are not, whereas all the high end scan tools are compatible to virtually all cars, trucks and bikes.

SCAN TOOL

So, if your a car owner / DIY mechanic, it is imperative to get yourself a decent  aftermarket VW-Audi diagnostic scan tool. If you own an Audi,  Porsche, Bentley, Bugatti, Lamborghini,  SEAT, Škoda or Volkswagen I would suggest that you invest in the USB Cable KKL 409.1 VAG-COM Auto Scanner Scan Tool for VW/Audi (Blue) for starters. This cable supports the ISO9141 and KWP2000 transmission protocols and is usable with VCDS lite downloadable from the Ross tech website absolutely free. I started out with this rig and later bought several dedicated scan tools as well as bluetooth dongles that work with cellphones and software for my tablet. None as good or even comparable to VCDS (VAG-COM) HEX-V2 which surpasses the performance of most generic OBD-II tools, but its VW specific.

ELECTRONIC POWER CONTROL

Limp mode limits the amount of power to your engine and transmission thus delivers poor engine performance. EPC (electronic power control) may be lit and Malfunction Indicator Lamp (MIL)(K83) may also be lit. 

Limp mode scan codes:-

000289 (P0121) - Throttle Position Sensor (G69): Implausible Signal

000290 (P0122) - Throttle Position Sensor (G69): Signal too Low

004243 (P1093) - Bank 1; Fuel Measuring System 2

000545 (P0221) - Angle Sensor 2 for Throttle (G188): Implausible Signal  

000808 (P0328) - Knock Sensor 1 (G61) Signal too High - Intermittent

05445 (P1545) - Throttle valve control system, Malfunction

05464 (P1558) - EPV throttle Drive - G186, Electrical malfunction in circuit

01314 - Engine control module / No Communications

17252 (P0868) - Transmission Fluid Pressure Adaptation at Limit

             

WIRING HARNESS

As can be seen from the above, all these Limp mode scan codes / faults are associated with a VW wiring  harness problem and is normally a connector problem but it can also be the a failed throttle body, a knock sensor, the torque circuit, a brake light. The gears inside of the throttle body can strip or becomes clogged with dirt. Remember the last resort is a failed engine control unit (ECU).

Volkswagen

Volkswagen

Volkswagen cars are extremely popular. In fact, they are so  popular that Volkswagen as a brand is the favourite car of many South Africans, besides being the most popular car sold on the South African market. Volkswagen cars are also popular elsewhere and are sold in virtually every country throughout the world; but its popularity and its global acclaimed robustness doesn't make it indestructible. 

Volkswagen cars give problems, in fact they are more troublesome now, than they've ever been. The reason, the ODB-II system with its ever increasing number of ECUs.  This system has several features that means well, like controlling toxic emissions, like giving you the best fuel efficiency;  and is capable of detecting minor issues or glitches before they actually occur, among so many other beneficial features.

However, like every coin has two sides, and as there are always two side to every story, there is also a reaction to every action.   Meaning for every beneficial feature of OBD-II there is a detrimental feature to OBD-II. OBD-II is essentially a computer system with a host of additional computer modules remotely placed through the body of the car, some of which have an effect on the Engine ECU. 

These modules or sub-ECUs oversee various features, like an airbag controller module/ECU that supervises the airbag. This module is connected to crash sensors placed in strategic positions in the car, that triggers when a crash occurs and ensure that the airbag is inflated within the required time frame. Then there is also an immobilizer module/ECU that supervises the starting process ensuring the correct code from the key transponder chip corresponds with its randomly generated code. There is also an ABS Brakes module, a Gateway module, a Steering Assist module, an Instrument Module, a Central Convenience module, a Radio module, to mention but a few. All of which are potentially sources of problems.

If we only look at the Airbag and the Immobilizer modules/ECUs, both will impede driveability and the starting of the car, by influencing the Engine ECU. If the Engine ECU doesn't received the expected signal from either, it would refuse to start the engine. The Engine ECU is the heart of the ODD-II and normally sits in the engine compartment or inside the car under the dashboard. All three these modules/ECUs mentioned, sometimes also referred to as nodes, are in within a meter of on another but here's the downside. 

To get them to sing in harmony they are connected together by a wiring harness. This wiring harness plugs into each and every node in the car, and also share a common twisted-pair wire-connection  called a bus which is terminate at each of its ends with 120 Ω resistors. This bus can be either Controller Area Network (CAN) or  Local Interconnect Network (LIN) or even FlexRay. Each module also has a power supply and an earth connection. All of these wire connections are potentially sources of problems.

The average car can have anything between 5 and 100 modules/ECUs, some ECUs have as few as six connections and others as many as 80 or 94 or even more. Each of these physical connections are prone to corrosion, metal fatigue and physical flexing due to suspension vibration and is a source of future problems. Some ECU's earth connection is solely made through body contact and if it looses contact due to vibration or water ingress, it will undoubtedly cause an error or errors. 

These errors are stored in the ECU's non-volatile memory which can at times be quite cryptic. I can say that without doubt that every "automotive technician" has misinterpreted DTCs and replaced unnecessary components in the process. Even returned cars to the owners claiming that they solved the problem but didn't, they were just under the misapprehension that they did.

If any connection out of this glut of connections becomes intermittent for some reason or the other, it would be like trying to find a needle in a haystack and there are so many "automotive technician" that have never touched a needle nor even seen a haystack, let alone find a needle in a haystack. Be that as it may, one of the advantages of OBD-II is that it increases the likelihood of a DIY fix, providing the fixer is fairly dexterous and have some electronic and mechanical knowledge and have access to a diagnostic scanner.

A fairly common plug connection that goes intermittent, is the one that connects to the throttle body. It supplies the voltage to the stepper motor that controls the throttle butterfly valve. This plug also sends feedback to the ECU so that it knows how wide open or close the valve is. So many mechanics insist on stripping the throttle body due to a throttle body DTC and claim after cleaning it, the problem was solved. However a few days later the error would be back. A word of caution, Don't suspect replaceable parts especially if it has less that 100 000 km on its clock. Exhaust the possibility that it's a possible wiring harness problem before replacing expensive items because they can never be returned to the agents after its been installed.

Another intermittent connection it the 6 pin plug that interfaces with the accelerator pedal. This is a common source of the dreaded EPC problem. In many cases, a squirt of electro cleaner may solve this problem. That's to say until it's triggered by something else. It's worth while to check the voltage supply stability and ground impedance between the 6 pin plug and the ECU. Remembering that the pedal's earth connection is grounded inside the ECU and the ECU is grounded to the body or chassis and not the engine. In some cases, the ECU will function normally because its metal casing is not earthed.

Also, don't be tempted to earth the pedal earth directly to the body when there is a  significant resistance reading. Rather replace that portion of the wiring harness that may have gone high resistive. Offset ground connections and ground loops can cause voltage drops and magnetic impedance which are major causes of noise hum, and interference in computer systems (ECU). So don't alter the the existing ground connections because it could introduce issues you've never experienced before.

Volkswagen Polo

Volkswagen Polo

The Volkswagen Polo Vivo is undoubtedlty the most popular, as well as the  best-selling car is South Africa. Looking at the top ten vehicles sold in South Africa, VW Polo Vivo takes first place, the Volkswagen Polo takes third place and the Vw Golf takes tenth place. Looking at the frequency of problems encountered with Volkswagen vehicles  in general, it appears that the VW Polo 2002-2009 models are far more reliable than the VW Polo 2010—2016 models. These models are prone to EPC problems and several Polo owners have complained that they encountered EPC problem with their cars with as little as 700km on their clocks.

The most troublesome generation 5, VW Polo seem to be the 2011 model, but the 2012 model takes the cake for the annoying knocking sounds coming from the suspension when going over speed bumps and pot holes.  But this knocking sound isn't unique to the Polo 2011 and 2012 models, it also affects the Golf Mark 7, the Volkswagen Transporter T5 and Polo GTI, etc.

It seems that somehow the strut mount bolts in the engine bay of these Volkswagens haven't been torqued properly. The rattling and knocking noise coming from the shocks occurs when driving over pot holes  or over speed humps, especially when the shock is fully extended or when driving slow.  In some cases the noise comes from coil-over assembly. These coil-overs squeek and creak at random and sometimes the rear ones squeak worse than the front ones. We found by removing the damper adjustment knob and tightening the 17 mm nut in the middle of your strut top,  and   holding the centre with a 7 mm allen key,  the noise is  somewhat reduced but is very disconcerting since these models are relatively new cars. 

Its probably best to re-torque these nut between 45-60 ft/lbs with a correctly  calibrated torque wrench. In my opinion there should have been a total recall on VW Polo 2010—2016 models for this problem. 

Loss of Power

LOSS OF POWER

On Sunday past, whilst taking my family for a drive along our scenic coastline on the Western Cape, I happened to see no less than three Volkswagen cars, each being loaded onto a roll-back. A VW Polo Vivo in Muizenberg, an Audi S4 in  Fish Hoek and a VW Scirocco in Scarborough. I couldn't help but feel awkward about my own Volkswagen Polo because after all, three out of three vehicles on the roll-backs were Volkswagen manufactured cars. I would have felt loads better if at least one of them were a Toyota or a Ford or a Honda. Understandable there are a lot more Volkswagen vehicles on the road than any other make, hence the higher failure rate.  

However, I instinctively pulled over for a chat with the driver of the Scirocco to inquire about the problem. It's owner Gwendaline. apparently parked her car to go for a walk on the beach and when she returned, had difficulty in starting her car. When it finally started , the whole car shook like her washing machine does in its spins cycle.  According to her, the Scirocco  is  really an excellent car with very few issues other than regular EPC light issues; and that its 18 inches tyres are a bit expensive. So we started talking about the EPC - Electronic Power Control and she seems really knowlegeable about it.  Our conversation went something like this.

Electronic Power Control

The EPC warning light, is just an indicator light powered by the Electronic Power Control circuit. Most people are under the impression that it indicates that there is something wrong with the engine when it light up. But this is not exactly the case, because the EPC light does come on when a brake light is fused or the fuel tank cap isn't properly closed.  When The EPC warning light flashes or stays on, it merely alerts the driver to a problem that may exists in your Volkswagen's throttle system. The throttle system encompasses  the throttle body, the throttle control motor, the accelerator pedal, the drive-by-wire electronics, the traction control, the cruise control, the stability control, the fuel delivery system and even the braking system and all their sensors, etc.. 

What does it mean when the EPC warning light turns on in a Volkswagen?

The throttle body motor opens and closes the butterfly valve located on the intake manifold which regulates the amount of air that goes into the engine, in relation to the position of the accelerator pedal. Implying the higher the air flow into the engine, the more fuel the ECU injects, thereby increasing  or decreasing the power output of the engine. When a problem is detected in the throttle system, a signal from one of the sensors triggers the  ECU into illuminating  the EPC  warning light. 


The Electronic Power Control (EPC) is just a part of the Engine Management System, which in turn is part of the overall On-Board Diagnostic II system. Normally when the a problem is detected that causes the EPC light to turns on, it also sends fault codes to the dashboard module or gateway module, vehicle model dependent. These fault codes can be retrieved by an ODBII scanner / smart phone, which are key to isolating the area of the throttle system that has failed. Most EPC light and ESP light problems will limit your Volkswagen's output power, commonly known as "limp mode".  

It is advisable that when either the EPC or ESP lights turn on, the problem associated with it be repaired timeously. A Volkswagen in limp mode should not be used to run errands, and since the car has sufficient power to drive it to  dealership or mechanical repair shop, it is best to do so. Normally once the fault / problem is remedied the EPC or ESP light will turn off. However, there are hundreds if not thousands of Volkswagen owners who have taken their Volkswagen cars into dealerships for repair, only to encounter the same EPC / ESP problem a day or two later.  Some of them suffer with EPC problems for months and I personally know of someone who had an EPC problem for more than a year. That's enough to drive the sanest person nuts.

________________________________________

My W Polo classic 2003 model's EPC light is on and there's no acceleration. My VW Jetta's dashboard displays the word  EPC, now it has no power. My VW Golf diplay the letters Epc, what can I do?  My VW Golf IV cluster shows both epc and esp and it won't revv up, nor go more than 70 km/h. My VW Sirocco 2017 model's epc light has come on again. My car's EPC light is on and I don't know what to do?  

ENGINE STALL / SHUTS OFF WHILE DRIVING

Engine stalls / shuts off while driving.

Of all the cars built by Volkswagen, the Jetta seems to be the most troublesome VW, and out of all the Jetta models manufactured, since its inception, the 2015 model seems to be the most problematic. Problematic  is perhaps isn't  the best adjective nor the most appropriate word that Jetta owners would use to describe their vehicles.  Most of them say their cars are, very scary and highly dangerous, because of the engine suddenly stalling,  especially in places where it's unsafe to stop. 

Female VW Jetta owners are now generally upset, afraid and some are even terrified to drive their cars, because of their frightful experiences with their cars losing power on the highway / express lanes, as the EPC and engine light turns on. They are fearful and generally worried that it could happen again. All of them convinced that it can lead to a very serious accident, also  stating that the car feels like a death trap when it stalls in fast moving traffic. Many of them feel it is unsafe for them to drive with their children in a car with the potential of being in a rear collision at any time, or get them all killed. They are disappointed and disgusted by Volkswagen personal for not caring about their complaints.

We're talking about new cars and well maintained cars, cars that are taken care of, most with less than 20 000 km on their clocks and one with as few as 30km on its clock, that needs to be towed to the VW service centers. To make matters worse,  roadside assistance sold with these Jettas have an ETA of 3 hours. And to crown the problem, VW agents can't seem to find the reason why these Jettas turn  off in mid travel, yet they are always replacing spare parts. They blame it on a central fuse which was not properly installed, or on the  wiring harness to the gas accelerator housing. Some blame it on calibration, yet it doesn't fix the problem. When a VW dealer was told that the car is unable to accelerate after stopping at a traffic light or at stop street, they echoed that they've never heard of this happening to any other Jetta before, yet this problem seems to be as common as sand.

 In fact it is really common on the 2009 Volkswagen  Routan -  traction control light comes on and the vehicle  completely loses power, engine shuts off while driving and the steering locks. If ever there was a   safety issue, then this is it. Then there is the smell of  gasoline or diesel inside the cabin which the service centers dismiss as an overfilled fuel tank which turned out to be leaky high pressure fuel pump on a 2015 Jetta. Then there is the cooling fan that runs at high speed after the ignition as been turned off, and as a consequence drains my battery.

When these Jettas switch off, nothing works not even the SOS roadside button, so it more like electrical than mechanical, though when the car goes into limp mode the steering system locks and the car cannot even be steered out of harms way. To add insult to injury, VW is unwilling to recall these Jettas and these problems don't seem to be covered by the  VW warranty. 

Somehow certain problems tend to be specific to certain Jettas models, for example, the 2004 and the 2015 Jetta seem to have engine problems though not exclusively.  Clutch clutch failure in the 2015 Jetta  is also common. The 2003 and the 2016 Jettas appear to have transmission problems though also not exclusively. The 2006 tend to have interior electrical accessories issues and the  2009 Jetta seem to have problems with their 'brakes' and ABS module failure. Jetta with FSI and TSI direct injection engines are subject to carbon buildup in the intake system which can cause power loss. It is wise to clean the intake manifold, cylinder head ports  every 30,000 kilometers..

Jetta SE V4 Turbo, Jetta CLI, Jetta S 2.0L, Jetta SE V4 Turbo, Jetta SE 1.8t, Jetta Trendline Plus 2L, Jetta TDI, Jetta TSI 1.8L

HOW TO FIX AN EPC PROBLEM

HOW TO FIX AN EPC PROBLEM

Electronics have taken the motor industry by storm, so-much-so, that electronic black boxes and discrete components have come to replace several mechanical systems. Case in point, Drive-by-Wire system, where a mechanical cable is replaced by an EPC (Electronic Power Control) system. Or a shared coil or carburetor is replaced by a set of individual electronically controlled coils or electronically controlled injectors, respectively . As a result, providing us with increased safety features, tighter and better engine control, additional creature comforts, convenience and so much more. 

Virtually every system in the modern day car is digitally controlled by a some Electronic control Unit (ECU) or a bank of dedicated on-board computers  distributed throughout the car, all of them networked to a Central Bus System. There are numerous bus systems used in electronics but CAN bus developed by Robert Bosch in 1986, has quickly gained acceptance into the automotive and aerospace industries. With the continued development of more complex ECU applications,  much larger quantities of data needed to be  processed, scores of more signals needed to be measured, and a growing number of other parameters needed to be optimized. 

CAN bus was the answer to surmount these problems though it is essentially a serial bus protocol used to inter connect individual sub systems and sensors as an alternative to conventional multi-wire looms. In a nutshell, cars have gone electronic processors, is firmware based, software driven and data analysed, artificially semi-intelligent and electronically complex.  All of a sudden automotive mechanics needed to learn loads of new words like microprocessor, microcontroller, quantitative analysis, electronic engine-management systems, potentiometers, sensors, signal processing, frequency response, memory-mapped  let alone how their individual functions. 

To add insult to injury, abbreviations like Controller Area Network (CAN), CPU (central processing Unit), RAM (Random Access Memory), EPROM (Electronically Programmed Read Only Memory), LAN  (Local Area Network), ADC (Analogue to Digital Converter), distributorless ignition system (DIS), etc, just flooded the motor vehicle repair market. 

Talking about abbreviations, EPC, is the official abbreviation for Electronic Power Control when referring to the Drive-by-Wire Torque circuit,  though it also stands for Electronic Pressure Control when referring to the Automatic Transmission.  When the Torque control EPC circuit fails for whatsoever reason, the  EPC Warning Light (K132) located in the instrument cluster lights up, which then could cause the car to enter into "limp mode", depending on the severity of the problem. Limp mode is a protective state that the car's ECU enters into when it recognizes that there is a problem with it's logic program. 

For example, when an expected signal value originating from a sensor varies significantly from the predetermined program  specification, the ECU then enters into a secondary/ emergency programme in order to protect the engine / transmission from damage. The ECU is constantly expecting a regular stream of signal values from various sensors, like for example the Throttle Position Sensor, or the Mass air Flow Sensor, or the Engine Speed Sensor, or the temperature sensor, etc. As long as these signals stay within specified parameters for certain operating conditions, the ECU performs faultlessly at controlling the engine. 

Due to  the rapid expansion of electronics in motor vehicles, automotive mechanics in general were over whelmed by the introduction of this new evolution in technology and as a consequence didn't stay abreast of automotive electronics, thus now seem to have great difficulty in solving electronic problems on client's cars. Replacing parts indiscriminately with the hope that they get lucky and that the actual faulty component is among the suspected parts that were replaced.  

Many, many, many VW, Audi, Skoda, and Seat owners can testify to this, since most have first hand experience of taking their vehicles into the service agent, only to get the car back after having to foot an enormous bill for replacement parts that probably weren't faulty in the first place, only to discover later that the problem the car was taken-in for, still persists.  EPC problems essentially have most VW "mechaicians" by the short and curlys.  But an EPC problem is not that difficult to eliminate if checked systematically instead of trying to trace it by replacing components by substitution.

DESCRIPTION OF HOW THE EPC WORKS

When the ignition is initially switched on, the Motronic Engine Control Module (ECM) performs a quick self diagnosis of all components that are important for the correct functioning of the Electronic Power Control. If all components pass the  diagnostic test the EPC light goes out. However, should  the Electronic Power Control (EPC) Warning Light not light-up when ignition is switched on, or if a  malfunction  is detected in Electronic Power Control system whilst the engine is idling, the Motronic Engine Control Module (ECM) will turn on the Electronic Power Control (EPC) Warning Light, sort of constantly.  When this happens, a DTC entry is made in the Motronic Engine Control Module, then its time to scan for Diagnostic Trouble  Codes with a scan tool.

NB! 

EPC also stands Electronic Power Control but also stands for  Efficient Power Conversion (EPC), Emergency Power Cut (EPC), Error Protection Code  (EPC), Event Process Controller (EPC), Embedded Personal Computer (EPC), Embedded Programe Controller (EPC), Erasable Programmable Chip,  Electronic Page Composition (EPC), Editorial Processing Center (EPC), Electronic Publishing Center (EPC), Energy Performance Certificate (EPC), Engineering, Procurement and Construction (EPC), Earnings per Click (EPC), Electronic Pressure Control (EPC), Electronic Product Code  (EPC), Enterprise Planning and Control (EPC), Every Penny Counts (EPC), Earth Population Control (EPC), Enhanced Power Control (EPC), 

....To continue.....

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

AUDI OIL USAGE

EXCESSIVE OIL USAGE ON AUDI A4

In a previous blog Audi Oil Pump Problem - Audi A4 Engine Noise, I mentioned the benefits of using VW 503.00 Long Life Engine Oil, but it seems that I was also mislead by the VW propriety oil specification the expanse of which I was unaware. This is probably the reason why my sister's A4 2.0L 2007 engine gave up the ghost. But as they say in the legal circles, "Ignorance of the Law is no excuse". Apparently as long ago as the year 2000 increased requirements compelled vehicle manufacturers globally to reduce exhaust emissions, minimize their carbon footprint, and improve overall fuel economy. Since motor oil plays a crucial  role in meeting these requirements,  the API's (American Petroleum Institute) old petroleum-based motor oils standards was abandoned by VW in favour of advanced cutting-edge synthetic motor oil formulations. As a result, the technologically advanced Audi engine designs required a very specific motor oil that met with Audi quality specification. 

Its newer models fitted with advanced fuel injection systems needs to  be lubricated  by this very specific motor oil formulations in order to guarantee optimal system reliability and fuel economy. These oil specifications started with VW 500.00 for models prior to year 2000 which has been superceded by VW 502.00. Then there is  also  VW 503.00, VW 503.01, VW 504.00, VW 505.00, VW 505.01, VW 506.00, VW 506.01, VW 507.00, etc, each applicable to either or both gasoline and diesel Euro standard engines. But certain oil specs are not suitable for certain vehicles. For example RAVENOL WIV III SAE 5W-30 is not suitable for specification VW 506 01. Meaning Audi engines with LongLife Service (QG1): Diesel-Engines (R5-, V10 TDI Pumpe-Düse) with or without Diesel Particulate Filter.  As well as  Audi engines without LongLife Service: R5-, V10 TDI Pumpe-Düse with or without Diesel Particulate Filter.

Topping up with conventional motor oil that does not meet Audi oil quality standards is therefore risky because the wrong motor oils could cause damage to internal engine components, somewhat increase emissions, reduce fuel mileage, and very likely void applicable vehicle warranties. The vehicle is also bound to use excessive oil and tend to smoke a lot more.

Ravenol HPS 5W-30 oil meets the Audi oil quality standard 502 00 and is  recommended for Audi A4 2005/2006 and on Audi A3 models equipped with the 2.0 Liter Turbo engine with FSI. Their fuel pumps are driven directly off the engine camshaft and lubricated with engine motor oil.  By not using the approved Audi motor oil  these models are subject to premature engine wear which will result in a loud ticking valve noise  after the engine has warmed up to its  operating temperature.  

Ravenol VMP Audi Oil 2010 - meets the Audi 507 00 Oil Spec and is recommended for use on Audi A3 TDI and 2009 - on Audi Q7 TDI models equipped with a Diesel Particulate Filter (DPF). Using non-approved Audi motor oil will results in increased oil consumption oil since it will be burning oil. Any non-approved TDI motor oils will clog the DPF  prematurely which is also  quite costly to replace. 

Since the VW oil specification and oil usage cannot be generalized across the Audi and Porsche ranges and old petroleum-based motor oils are no longer usable, it is no wonder that Audi owners are complaining about excessive oil use. Some Audi owners have driven as little as 600 miles or about 950 kilometers before the engine oil low light goes on and the buzzer drives  the m crazy. This is probably because they topped-up with non synthetic oil. Funny enough, Audi stresses the  point of not adding petroleum-based motor oil to its synthetic brands.

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.

________________________________________________________________

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.

 ________________________________________________________________

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.