Showing posts with label EPC warning light. Show all posts
Showing posts with label EPC warning light. Show all posts

Thursday, June 22, 2017

My EPC light

My EPC light

If you've had your VW, Audi, SKODA or SEAT for a while, you're probably familiar with the EPC light and already experienced its wrath. If you haven't encountered the EPC warning light as yet, then you are definitely one of the lucky ones, because I know of several VW Polo, Seat Ibiza,  VW Jetta, VW CC, Passat, Audi A3, Audi A6, Seat Leon and even Porsche owners with odometer readings as low as 1500 Kilometers, who got spooked by the EPC light when it first stuck. This EPC light is known to trigger instant panic and fear in many VAG car owner, and I don't blame them, since it can be a scary and dangerous experience, especially when the car goes into limp mode when you're overtaking or the engine just dies when exiting a freeway  off-ramp or when entering a highway on-ramp during peak hour traffic.  

Electronic Power Control

However, if you have no idea what an EPC light or an EPC fault is, nor why this warning light turns on, then you should do yourself a solid and continue reading. In a nutshell, the EPC warning light is a standard feature in all ODB-II compliant models of Volkswagen, SEAT, SKODA and Audi vehicles. Most of them, are fitted with 'drive-by-wire' technology, though neither are exclusive to VAG cars. And when I say VAG cars, I also mean  Porsche, Bentley, Bugatti, Lamborghini and Ducati. Toyota, Honda, Ford, Mercedes also has it, in fact, virtually all cars manufactured post 1996  have an EPC warning light. EPC is an acronym for Electronic Power Control, and its a  warning light that resides inside the instrument cluster display.

EPC Light

Nonetheless, the EPC light is not all doom and gloom. It is there for a reason, and that reason is to safeguard the car and the engine from damage or destruction, especially considering what they cost to repair these days, let alone the cost to have an engine overhauled. Many people are under the misapprehension that the EPC light indicates an issue  with the cars  computerized system, whereas mechanics tend to echo that the EPC light indicates  a potential engine malfunction, though that's not strictly true either.  


MIL 

Before we continue, I just needed to add that when the engine malfunctions, it illuminates the Malfunction Indicator Lamp (MIL) aka Check engine light (CEL), which is indicative of  a computerized engine-management system malfunction. It even has an amber/orange icon of an engine, so as to draw your attention to the engine. Furthermore if this amber icon engine light is steadily illuminated, it indicates a minor engine fault but when it blinks it signifies a major engine fault. On the other hand, the EPC (Electronic Power Control) warning light  is a distinctly separate light from the MIL or CEL because it is related to a different function.

The more appropriate answer to 'What is an EPC light?' would be that the Electronic Power Control warning light, indicates a malfunction in your VW, Audi, SKODA or SEAT's  throttle control system, though once again that's also not totally accurate either.  So let me throw so light on the subject. The EPC light is in fact a diagnostic test light. So when the car's ignition is first switched on, the EPC light is illuminated for about three seconds. If there are no faults in the EPC system the light will automatically extinguish.

Drive by Wire

This three second time period is the duration of a self-diagnostic test. Effectively the Motronic ECM (J220) checks for malfunctions  in the Electronic Power Control (Torque system) accelerator system (drive-by-wire system), which includes the Throttle Body Drive Stepless Motor (G186) with its dual   independent Throttle Drive Angle Potentiometers (G187 & G188), the Accelerator Pedal Module with its dual independent Throttle Position Sensing Potentiometers (G79 &G185), the wiring harnesses that connects them all together and its associated sensor inputs from the Cruise Control  System, the Anti-lock Brake System (ABS), the Oxygen Sensor Control, the Automatic Transmission and the Air Conditioning System, etc. 

Charge Air Path

Here Air conditioning system mean all components involved in conditioning the air in the inlet manifold prior to combustion, implying the Throttle body / Mass Air Flow (MAF) sensor G70 and not A/C as in HVAC.  That being said, the functionality of an Electronic Throttle Control (drive-by-wire system) can regulate the Charge Air Path far more accurately than a physical cable between the accelerator pedal and the throttle valve. 

NonVolatile Memory

This being the case, by the time the EPC light illuminates on the dashboard  in response to some sensor detecting a problem  whilst driving, the problem already occurred.  The  EPC warning is just a way to tell you that there  was a glitch in the EPC (drive by wire system) and generally remains lit until the fault is cleared. The EPC light is known as K132 and is turned on by the Motronic ECM by providing the Ground  connection that keeps the light burning. At the same time, a DTC is registered and stored in non-volatile memory for later inspection.

Limp Mode

So the key piece of equipment to solving any EPC problem or issue is a diagnostic scanner. The fault below shows that the brake light switch F was the culprit that caused the EPC fault. Bearing in mind, that the Cruise control get its cancellation signal from the brake light when the brake pedal is depressed. When a brake light is fused or the dual contact brake switch goes open circuit and can't provide the requisite signal, the cruise control cannot be cancelled. The ECM detects this condition and construes it as a safety issue and sends the car into limp mode

Fault Codes

Essentially the EPC circuit prevented an accident from happening. Implying the brakes would work but the engine would still run at high rev set by the cruise control, meaning the brakes would be ineffective to bring the car to a stop. For safety reasons the EPC system closes the throttle valve to a predetermined position the brake pedal and the accelerator pedal are depressed simultaneously. However if the ECU detects that the brake was depressed before the accelerator, then acceleration will be carried out. 

1 Fault Found:
16955 - Brake Switch (F) 
P0571 - 35-10 - Implausible Signal - Intermittent

The fault below shows  that there is  an electrical malfunction in the Drive by Wire  circuit causing the EPC light to illuminate. After clearing the fault code, the EPC light just comes back on. The ECU was suspected and replaced but didn't solved the problem. It turned out that the  wiring harness between the ECU and the instrument cluster.

1 Fault Found:
18084 - EPC Warning Lamp (K132) Circuit: Electrical Malfunction 
P1676 - 35-00 - - 

The fault below  was on an Audi where signal from the Transmission  Control Module (TCM)  to the ECU was intermittent causing her to go into limp mode and idle really rough. Turned out that the TCM got wet from rain water that leaked into the carpets.  

1 Fault Found:
18265 - Load Signal: Error Message from ECU 
P1857 - 35-10 - - - Intermittent



Sunday, May 8, 2016

SEAT CHECK ENGINE LIGHT PROBLEMS

SEAT COMMON PROBLEMS AND SOLUTIONS  

The supermini SEAT Cordoba based on the Seat Ibiza Mk2, has been around since 1993. When the Volkswagen AG took over production from the Spanish auto maker, it was  replaced by the Ibiza ST /  Seat Vario built on the same platform as the Mk4 VW Polo and the Skoda Fabia. They are available in coupe, saloon and estate in 1.2, 1.4,  1.6, 1.8 and 2.0L petrol and 1.9L diesel engines with either a 5-speed manual or 6-speed tiptronic gearbox, and were in production until 2009. These cars  were  renown  for their good performance, handling and its safety features, but like all cars, they tend to develop common problems after a few years. Pero es un buen coche para comenzar en Mexico y España.

The most common of all engine problems was engine misfiring and in the process turning on the Seat check engine light, or the Seat Ibiza engine warning light, or  Seat Altea engine warning light, or the Seat Leon engine warning light, or Seat Arosa engine warning light, or Seat Leon TDI engine warning light, or Seat Cordoba  engine warning light. The most likely cause of this problem was the coil pack or the spark plug leads which needs replacement. A telltale sign was excessive  shaking when idling. This was very prevalent when coming to a stop street or traffic light or when starting first thing in the morning. Unlike cars of yesteryear  that had a single coil and a distributor that supplied a spark to the upcoming spark plug; these cars have its own coil pack for each cylinder. More coils packs  just increased the amount of things that could go wrong, and do they go wrong.


Another common problem with the Mk4 was a lack of power which also turns on the Seat Ibiza engine diagnosis warning light or Seat Cordoba engine warning light.  The cause of the problem in most cases is  the MAF (mass air flow) sensor. A telltale sign is a lack of power at high speeds and or just  poor overall acceleration. It is always worthwhile to try and clean it with compressed air but if this didn't solve the problem, replacement is the only option.  Once repaired,  one would feel an immediate improvement on performance. 






Many Seat Cordoba window wipers also just suddenly stops working which sometimes turned out to be the wiper linkage that seized and sometimes turns out to be the wiper motor and sometimes both. Then there is the ever creaking noise sometimes sounding like an exhaust rattle coming from the front suspension when driving over speed bumps or rough surfaces. This turned out to be the anti roll bar bushes which after replacement solved the problem. A problem that plagued the automatic models is the ever noticeable red oil mark on the ground underneath the car. The origin of the leak is either gearbox seal leaking or the selector shaft seal that is leaking. Seal replacement normally stops the leak. Failure to address this problem ends up with the gear lever stuck in park with the PRDN light glowing right red on the dashboard. The gearbox  grinds when attempting to put the car into drive but will kick in with an huge thud.

Then there is the breaking distance problem on certain models (Ibiza, Toledo, Cordoba, Leon, Vario and Inca) fitted with ABS, needing a lot more force to be applied to the brake pedal to get the car to stop. The cause of the problem turned out to be tension cracks that develop in the vacuum pipe going to the brake servo near to the connections area. This is in fact a manufacturing fault that can be replaced under recall free of charge. After replacement of the vacuum pipes breaking was back to normal.

Ibiza, Altea Toledo, Leon Toloedo, Cordoba  and Alhambra vehicles fitted with a 3 and 4 cylinder pump injector engine with 2 valves per injector is prone to the bolts on the tandem pump cover that breaking off.  This was also a manufacturer  fault and vehicles were recalled to have the pump checked that was supplied by a certain manufacture.

Seat Ibiza and Seat Toledo and Seat Leon with VINs ranging from VSSZZZ1MZ1B036908 to VSSZZZ1Mz1B044227 seem to have a problem with head airbag unit which would fail to activate under certain collision conditions. Seat Altes,Toledo and Leon with 2 L TDI engine and  6 speed manual VIN ranging from VSSZZZ5PZ4R000048 to VSSZZZ5PZ4R017390 and VSSZZZ5PZ5R000026 to VSSZZZ5PZ5R103620 and VSSZZZ5PZ6R000009 to VSSZZZ5PZ6R001638  have flywheel problems that was also recalled for replacement.

The Seat Cordoba 1.9 TDI also developed starting problem when not driven for a day or two. But will eventually start after several attempts, idling very rough and smoking. In some cases it just drained the battery as well. But once she started it will start every time thereafter until left to stand for a day or two again.  This was caused by the diesel pipes sucking in air causing the diesel to flow pack towards the tank. The cause was a leaking diesel filter. A very annoying problem with some Mk4 is the drafts that comes in through door seals. It seemed that these rubber seals tend to collapsed after 5 years. Another thing is the coolant sensors / temperature sensors are generally of a very poor quality on all VW/Audi/Seat/Skoda group cars. They just tend to go faulty all the time. Surprisingly most of these problems are also prevalent in VW Polo range, after all SEAT is just another Mk4 VW Polo that has been badge engineered.

Tuesday, April 19, 2016

EPC DASHBOARD WARNING LIGHT

EPC DASHBOARD WARNING LIGHT

VW, Audi, Skoda and SEAT vehicles are crammed with wonderous technology, ranging from various electronic modules that overseas their general functionality to hoards of sensors that monitor how these vehicles behave and actuators that respond to software controlled decision making elements. One could say that collectively they give cars a degree of Artificial Intelligence and their seamless integration makes motoring a lot easier. But when something goes wrong, there is also a swarm of warning lights on the instrument cluster that will flash at you until you take corrective action. However, knowing exactly what each warning light flashing on its dashboard is trying to tell you, is a completely different story. Even though some of these light are self explanatory and fairly obvious to understand, others are not, and  can be interpreted by looking in the owner’s manual. Knowing what these warning lights mean is really important to drivers because they can preempt a potential breakdown or full-on engine failure, insulating you from expensive repair bills.

As a general rule, warning lights illuminated either red or amber (yellow /orange), though a blue light is often used to indicate high beam and green lights are used to mean indicate left and right  turn signals. On a VW Polo a red warning light emphatically means that something needs to be done immediately. For example, the Oil pressure warning light, or the low brake fluid level light, or the parking brake warning light, or the Coolant level low / coolant temperature high light, illuminates red or flashes red as a danger sign and needs immediate attention. Failure to remedy can result in the engine seizing, the brakes failing, damaging your rear disks and brake pads, or the engine overheating resulting in a possible blown head gasket or worse, respectively. On different model VAG vehicles, the use of red and amber light may overlap. 

An amber / yellow /orange light  on the other hand serves to be rather informative and draws the driver]s attention to a potential problem or a problems that needs to be remedied soonest. For example the amber Anti-lock braking system (ABS) light, or the amber Airbag light, or the amber Immobilizer light, or the Brake pad wear light, or the Engine fault Onboard diagnosis (OBD) light, none of which will impede driveability nor endanger the driver. But this isn't strictly true especially when encountering the dreaded yellow EPC light


WHAT IS AN EPC LIGHT?

EPC stands for Electronic Power Control and has  much to do with controlling the electronic throttle hence it is sometimes referred to as the "Electronic Pedal Control". Probably because the throttle valve is actuated by an electric motor rather than a physical cable between the accelerator pedal and the throttle control valve. In essence the engine control unit responds to the sensor on the accelerator pedal and sends a corresponding command to the throttle valve positioner via four wires which is commonly known as "Drive by wire". But the EPC is much more than just an Electronic Pedal Control. Any malfunctions in the either the "Drive by Wire" circuit  or its associated sensors are detected by self-diagnosis and indicated by the EPC warning light.

The Electronic Power Control (EPC) is a circuit made up of various engine components or sub circuits that collectively addresses torque. In reality it should have been called "Electronic Torque Control". Should  a problem arise in the torque system, it correspondingly illuminates the easily identifiable yellow/amber/orange word "EPC" in the instrument panel.  The EPC circuit's decision making elements are embedded into the ECU which is responsible for the electric throttle valve positioning and overall torque-oriented engine management.

As such the ECU has to gathers all torque demand inputs in order to correctly calculate the appropriate control actions. These inputs includes, the Engine speed, the Engine load signal fetched from the air mass meter, the Vehicle speed, the shift point of an automatic gearbox, whether or not the air conditioner compressor is ON or OFF, whether or not the the cruise control system is engaged, whether or not the Traction Control System is engaged  or the braking  system is applied.

The combination Brake light / brake pedal switch provides a braking input to the ECU, failure of the switch to send data of the drivers foot on the brake pedal can trigger the EPC light in certain VAG vehicles, but definitely on the VW Polo. Don't be fooled by the brake lights that are working, when the brake pedal is depressed because it does not imply that the brake pedal switch is functioning as it should. In similar fashion the Clutch Pedal Switch provides cruise control input to the ECU, engaging the clutch, automatically disengages the cruise control which could also trigger an EPC episode.

This EPC light will come on when there is a problem:-

1) With either of the accelerator pedal senders.
2) With either of the throttle angle senders.
3) With the throttle valve control unit
4) With the accelerator / throttle harness.
5) With the throttle adaptation.
6) With grime and carbon build-up in the throttle body. 
7) If the the Throttle Valve Control Unit is replaced.
8) With the Brake Light Switch
9) With one of the Knock Sensors.
10 With the Mass Air Meter (MAF).
11) with the Engine control unit
12) With the Ignition system
13) With the Fuel injection system
14) With the ABS
15) With the Power-assisted steering system
16) With Lambda regulation (fuel consumption signal)
17) With the Alternator
18) With the TCM

Bearing in mind the throttle valve control unit is located on the intake manifold and needs to ensure that the engine is supplied with the appropriate and proper air flow. By implication the MAF measures the air flow and should there be a problem with it, the  ECU will not be able to calculate the proper torque and possible go into EPC mode. The consolation is that every fault that occurs would normally create a DTC entry. So the best way to determine the cause of the EPC light coming on, associated with loss of power and limp mode, is to do a diagnostic scan. 


Links to other EPC Problems!
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Saturday, December 26, 2015

EPC Q & A REVISTITED

EPC Q & A REVISTITED

Of late, Vag vehicle owners are experiencing Electronic Power Control problems more frequently than ever before yet most VW, Audi, Skoda and Seat still have no idea what an EPC fault is and what causes the EPC light to turn on. To add insult to injury some VW, Audi, Skoda and Seat service agents tend to "repair" these faults by trial and error, costing the vehicle owners exorbitant amounts of money only to later discover that the fault persists. The EPC warning light can be found in selected models in virtually all makes of cars and is not limited to just Volkswagen Audi, Skoda and Seat vehicles. Volkswagen Audi, Skoda and Seat use Electronic Power Control in their drive by wire vehicles as a safety feature which in my opinion isn't all that safe. Case in point, I have had my VW Polo go into limp mode whilst overtaking a car in a two way street.  It stalled at the very moment when I was cutting-in in front of the said car, causing its driver to frantically brake and swerve to avoid colliding with the rear of my car because  suddenly I wasn't accelerating any longer. Not to mention the on-coming car, which swerved toward the shoulder of the road since my car was straddling the white line. My EPC problem turned out to be the incorrect octane fuel.


Be that as it may, by the time the EPC light illuminates in the dashboard, in response to some sensor detecting a problem, the problem already occurred in either the torque control, traction control, throttle body and sensors, accelerator pedal sensors, cruise control,  fuel supply or ignition systems. Essentially the epc light is just a way to tell you that there is a problem with the drive by wire system and generally remain on until the fault is cleared.  At the instant that the EPC light illuminates, the  ECU flags a DTC which is then stored in the relevant electronic control module. This DTC gives a fair idea of the suspect system but cannot pinpoint  the culprit component. 


QUESTION?

Anonymous says:- Hey I have a 06 Passat 2.0t and I am reading all of these stories on the EPC my check engine light was already on while I was driving but the car was good. I was on my way to work after stopping at the gas station and my EPC light came on and my car stalled on the highway and has not came back on. The lights windows and everything works but when I try to turn the car on it attempts to turn but never does. 


ANSWER!

From your description I understand that after your EPC light came on, your car won't restart. So you checked the light and windows which tells me you suspected that the battery may have run down and perhaps not strong enough to turn the engine over.  But you also mentioning 'check engine light'. A combination of check engine light and EPC light is emissions related and if your car's emissions exceed a predetermined level, the ECU will prevent the engine from starting. Its best that you have your car scanned to see what DTC it threw out. 


QUESTION?

Musa Brain says:- Hi there. I have a VW polo vivo I have the EPC light on when I'm driving slowly and also when I'm reaching a stop sign and hit the clutch pedal it turns off and when I start it in the morning it turns off so I have to rev it for it to idle but after some few minutes the EPC light comes on. Please help?


ANSWER!

Musa your description of your EPC problem seems that you car doesn't idle fast enough. I assume that its drives normal whiles on a higher rev. It quite evident that it switches off when you come to a halt and whilst it's cold. I suspect that you have a blocked air filter problem that doesn't allow sufficient air to the MAF, but I could be wrong since you provide no DTC's. It could also be a blocked fuel filter that starves stichiometricity since torque is determined by both  air and fuel. 


QUESTION?

Bogdan Iova says:- When I swich key on the EPC light not apear and teh engine not start. Golf 1.6 16V 


ANSWER!

Bogdan, you really haven't given me much to work with here, but off hand it seems that you may have a blown fuse that powers the instrument cluster. Because the moment you turn on the ignition key, the OBD II system does a self  diagnosis by turning on all the dash board lights for about 10 seconds whilst running the test.  It then turns off  those light related to the circuits that function normally and leaves those lights on, for circuits that fail the test.  So, if you EPC light does come on when you turn on the ignition , then goes off,  you don't have an EPC problem.   However if your engine won't start it's obviously cause by something else. It could be that your battery has reached end of life. If the engine doesn't turn over, even the starter could have packed-up. But if it does crank and won't start, check your fuel gauge to at least determine that you have fuel in the tank.  Related to this could be your ECM Power Relay, your fuel pump relay or the fuel pump itself. Without more info, this is about all I can help you with. DTC codes would have been helpful.


QUESTION?

Anonymous says:- Hi there, I have a 2003 polo 1.6, EPC light is on and when it's idling can't rev it, checked and cleaned the throttle body and still same issue, ran a diagnostics check and it says something about the pedal, please help?  


ANSWER!

Hi Anonymous, you seem to have a classic EPC problem but for the benefit of everyone else, it would have been great to share the DTC codes that you recovered. I suspect it must have been one of the following codes since you mention the error code said something about the accelerator pedal.

18038  P1630 Accel, Pedal Position -G79 signal too small  (low)
18039  P1631 Accel, Pedal Position -G79 signal too largely (high)
18040  P1632 Accel, Pedal Position -G79 supply voltage  malfunction

18041  P1633 Accel, Pedal Position -G185 signal too small
18042  P1634 Accel, Pedal Position -G185 signal too largely
18047  P1639 Accel, Pedal Position -G79 & -G185 out of range 

You also mentioned that you checked and cleaned the throttle body. If you dismantled it in anyway, then you need to redo adaptation, else the ECU would have no idea how wide the butterfly valve has opened.  Remember there is no throttle cable connecting the accelerator pedal to the throttle housing. This is known as a drive by wire system and it communicates the driver's torque demand to the ECU. The two potentiometers in the accelerator pedal assembly communicates the pedal position directly to the engine control module (ECM) using two separate signals, one signaling the pedal physical position and the other indicating rate of pedal movement.  You will need a scan tool to do the adaptation because any faults in memory must be cleared before adaptation can be done. 


The most common problem is the accelerator pedal itself. One or both of the potentiometers go high resistive/ intermittent and the accelerator pedal assembly should be replaced as a single unit. A tell tail sign of accelerator pedal trouble is that the engine revs higher than 800 rpm and at times the rev counter rises and falls continually whist idling, going as as high as 2000  rpm. If this happens, grab hold of the pedal whilst the car is idling and pull the pedal upwards, away from the floor. If the revs reduce and the surging stabilizers, replace the pedal. The image above shows idling whilst engine in surging and  the image below shows idling with the pedal pulled up.



Thursday, July 30, 2015

EPC Q & A

EPC Q & A

So many Audi, VW, SKODA and SEAT owner are having EPC light nightmares. Sending their vehicles for EPC repair which are often misdiagnosed, costly, ineffective and futile because most mechanical repair personal are not electronically trained hence have no idea of  digital logic and isolation procedures.  Modern cars are strewn with sensors and actuators, network buses, electronic control modules driven by software. To quote a line in Turks and Caicos which goes something like this "... everything changes. I used to be able to take a wrench and get under my car's bonnet and fix my car. Now you need a degree in electronics. Even easy things are difficult now." Replacing automotive components does not have to turn into a 'wild goose chase' where guess work is based on trial and error which now has become the order of the day.  That approach just scares everyone. Upload the diagnostic scan of your car now, so that I can analyse for you before you go ahead and buy expensive parts only to find out that the DTC was incorrectly interpreted.




Question?

I'm Lorraine from long beach. I don't know who you are but you are a God to me. I've been searching the web for months for specific and in-depth information on the "death light" (EPC) appearing on my '99 Volkswagen  Beetle. I have studied your entire blog and will now have a very interesting conversation with my German Car mechanic on how he can detect once and for all the problem. Already $1,000 in with no results. Thank you. I hope I don't have to sell the car just yet (to whom, I have no idea) throttle body replaced-twice so far-but hmm that Cam Bus section is interesting. My radio went into Safe Mode months ago and then spontaneously came back on (we do not have the code) so maybe we should check that path out as well. Again thank you.

Answer!

Hi Lorraine, since you don't say much about the specific problem that you are having other than the "death light" (EPC) appearing on my '99 Beetle, I really can't comment on it. However since it is EPC related, your problem has something to do with fuel delivery and engine torque electronics. Bear in mind that your fuel is under pressure from the tank to the injectors and that the ECU receives inputs from the various pressure sensors. If any of these pressures are below spec, it can trigger an EPC problem. For example, if your fuel cap does not seal properly the low fuel pressure sensor G410 will send a error signal to the ECU which can trigger an EPC fault. Likewise if the fuel regulator sensor cannot equilize the fuel pressure from the high-pressure fuel system it will trigger an EPC fault. Suppose If you were driving on an incline like an on-ramp to a bridge and didn't gear down sufficiently for you Beetle to swiftly climb with ease, the likely hood is that detonation would occur. If this happens, the knock sensors would inform the ECU which translate detonation as insufficient torque and trigger the EPC circuit - limp mode and EPC light. There are several other EPC possibilities but without a diagnostic scan it is difficult to pin point the problem.


Question?

Anonymous. 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!

Hi there. Since you don't have  diagnostic scan its difficult to help you however, the mere fact that you don't have dash light makes it very obviously that you have electrical problems or wiring harness problems. And since your scan tool didn't find any DTCs, further proves that this is the case. The dashboard is normally directly connected to the OBD port in the driver's cockpit and since you have no dash lights you most likely have missing voltages on the OBD port which is most likely needed to perform a proper and correct diagnostic scan. Check your fuses on the terminal 30 line and the relay that supplies the terminal 15  supply line. Once you've exhausted everything else, as a last resort your dash control module could be faulty. Anyway, the acceleration peculiarity that you are describing probably has nothing to do with the dash electronics. Since you car has drive by wire, which is totally electronic (not throttle cable), torque is determined by the ECU which will open the throttle valve logarithmically based on its load and terrain, thus there is no physical correlation between the accelerator pedal and the throttle valve. So, no I don't think it needs alignment but seeing you have an OBD-II scanner, its quite simple for you to just redo the adaptation (described in a previous blog) and take consolation in the fact that you have eliminated it as a problem.

Question?

Hi I have a problem with EPC it came on since yesterday, am worried please help.

Answer!

My friend, you really not giving me much to work with here. But I suggest that read through my blogs pages related to EPC, torque, drive by wire, accelerator pedal sensors, knock sensors,  throttle adaptation, engine RPM sensor, etc. Perhaps if would shed some light on your EPC problem. Remember that EPC problems are related to what the car was doing at the time the light came on. for example, spirited driving / towing / start stop peak hour traffic, etc, Anyway the best way to find blog pages relating to your EPC problem , is to type your search word (EPC / drive by wire, etc) in the search box I provided in the top left hand corner on the first page of my site and click on the miniature magnifying glass to run the search. Happy searching.

Question?

Hi everyone, I would really appreciate some advice from you all. I have a 2002 (52) Ibiza 1.4 Sport (100bph), and have some issues with it. Background: Since day 1 it has occasionally thrown up an EPC warning light, followed by an engine electrics light. They would go away after a day and not return for several months. I had the logs read by a Seat dealer during a service and they said it had shown an intermittent Lambda filter error, and that it would cost £240+ to fit a new one. I passed. Over the last month, this has become an every day occurrence. The EPC light will come on seemingly as I just try to pull away from stationary. The car sometimes (half the time) notably stutters when this happens, then pulls away normally. If I restart the engine, most times the EPC light will go off, but the engine light will stay on. Then, more weirdly, the car has started occasionally stalling at random. No judder, no rough idling, I'll be slowing down towards a roundabout or into traffic, and whilst idling (coasting on the clutch) as I slow down, I'll notice the battery light come on, and the power drop out. Once, the battery light came on, but I was able to rev the engine up and it recovered - the battery light then went out. Mostly, I need to restart the engine though. I took it to a garage called Vee Ws for its annual service yesterday and asked them to look into it as well. They went with a cautious (on my finances) approach, and said they'd do the full service and that hopefully that on its own might rectify some of the issues. After the service, they said the logs showed some intermittent issues but nothing serious. They reset the onboard computer to its basic/default settings and said they hoped that would sort it. They also said they noticed the throttle body was pretty dirty (done 71,000 miles), and that if the service doesn't sort it, that they would try to clean that up and see if it did the job. Anyway, 10 minutes after I pulled away from the garage, the lights came back on and today the stalling re-occurred. I feel like this could turn into one of those 'wild goose chases' where its a case of trial and error, replacing different parts to see if it works. This scares me greatly! Has anyone experienced any similar symptoms, or would anyone recommend going to a proper Seat Dealership/Services team to take a look? I wonder if maybe they may be more likely to find the underlying fault? Having said that, I've always found Vee Ws in Bristolonia competent and most importantly, cost-effective. It may be possible to ask them to try and source used-parts while they try different 'fixes'.. Thanks for any advice, Jamie

Answer!

Hi Jamie,  the fact that your SEAT occasionally throws up an EPC warning light, as well as  the engine electrics light, says that your problem is more likely emission related, hence your intermittent Lambda error. Normally only torque and fuel related problems triggers the EPC light, meaning the engine light doesn't come on. Engine light only comes on with emission related issues.  Considering the age of your car it is possible that the Oxygen censor could be glazed over (end of life) or its wiring connector could be intermittent. The oxygen sensor is a feedback mechanism that instructs the ECU to increase or decrease the fuel supply hence shuddering. But this may not be definite. Without a diagnostic scan, I  am more inclined to say it could be your throttle body sensors not only because your service agent said it was dirty but because of the stalling and stutters on pull away. This seems like the throttle valve isn't providing an adequate air supply when its needed. However if they serviced your SEAT and did the adaptation as they said they did, then its unlikely the throttle body else adaptation would have failed, even though they said its dirty. So its more likely to be your accelerator pedal sensors. I mention this because  the car switches off when you decelerate, implying while your foot was on the accelerator it was OK but by taking your foot off the accelerator the condition changed and the ECU picked of this which could be due to 1 or both intermittent potentiometers. When you initially start the car  the ECU does a self-test by switching on all dashboard lights and if no problems are detected turns them all off. So when you start and the EPC light turns off, at that specific point in time there is no problem, but half way through acceleration while driving the problem is detected and the ECU switches he car off. Intermittent DTCs that do not reoccur during four driving cycles, are automatically deleted from the system which explains why the EPC light goes out after a day or so and doesn't show up months later. Lets have a diagnostic scan and I will have another crack at analyzing your problem.


Saturday, July 25, 2015

INTERNAL CONTROL MODULE MEMORY ERROR

INTERNAL CONTROL MODULE MEMORY ERROR

DTC error 65535 (Internal Control Module Memory Error) suggests a problem was caused  within the said module. However, Electronic Control Modules are generally fairly robust and are designed with a MTBF of 1 million hours. My experience with electronic repairs over the past 30 years does not confirm this since I have had tons of electronic components failing during this time that was'nt expected to fail for at least another 10 years. Be that as it may, an Internal Control Module Memory Error may not even be caused by the module, so it should be the last component to suspect and replace because they are normally not cheap. Firstly check the battery Supply Voltage  and verify that it is constantly about 12V or higher. Also make sure that the alternator is charging, since a faulty alternator can lead to a slowly discharging battery not able to supply the minimum voltage required by the module that is flagging the  65535. Next check to wiring harness to and from the "faulty" Control Module. Make certain that the module has a ground connection (earth). If  VCDS displays an unexpected result or displays that the controller refused the command, it is most likely due to the wiring. Under intermittent wiring conditions it is generally difficult ifnot possible  to clear a  65535 (00-10) or (35-00) or (35-10) or (37-10). Wiring harness and its connectors are prone to corrosion due to condensation especially in cold weather. If needs be, unplug the connector and clean them and if possible check the physical contact with an ohm meter (but disconnect the battery first). Any Internal Control Module Memory Error associated with the Power steering  and ABS are critical and should be attended to immediately. Internal Control Module Memory Error associated with Airbags should be treated with caution since interrogation of the airbag with a scan tool could inadvertently trigger the airbag or turn on the airbag light which can only be switched off by replacing the airbag module. As can be seen below, virtually every electronic module can be a victim of 65535 - Internal Control Module Memory Error and as far as I am concerned, it most unlikely electronic design and quality control  will permit such modules to be installed in production units. The lateral acceleration sensor tend to cause an 65535 airbag error, the vacuum hose inside the ECU taking pressure to the barometric sensor tends to cause a 65535 error in Jetta's, barometric sensor itself tends to cause 65535 in Skodas.  As a last resort try replacing the module concerned.


Address 01: Engine
Chassis Type: 17 - VW Golf Citi
Part No: 6KS 906 258 k
Component: 1.4 MP9.0 26ZA0003
Shop #: 2227355880
65535 - Internal Control Module Memory Error

Address 02: Auto Trans
Chassis Type: 9M - VW Jetta IV
Control Module Part Number: 01M 927 733 KT
Component: AG4 Getriebe 01M 4891
Software Coding: 00000
Work Shop Code: WSC 00000
65535 - Internal Control Module Memory Error

Address 03: ABS Brakes
Chassis Type: 6Y - Skoda Fabia I
Part No: 6Q0 907 379 D
Component: ABS/ASR 5.7 FRONT V00
Coding: 00124
Shop #: WSC 13765
65535 - Internal Control Module Memory Error 

Address 03: ABS Brakes
Chassis Type: 1J - VW G/J/B Mk4
Part No: 1J0 907 379 AB
Component: ESP 20 CAN V005
Coding: 00214
Shop #: WSC 31414
65535 - Internal Control Module Memory Error

Address 03: ABS Brakes
Part No: 1C0 907 379
Component: ESP 20 CAN V005
Coding: 18945
Shop #: WSC 01317
65535 - Internal Control Module Memory Error

Address 03: ABS Brakes
Chassis Type: 6Y - Skoda Fabia
Controller: 6Q0 907 379 G
Component: ABS 5.7 FRONT V20
Coding: 00044
Shop #: WSC 13765
65535 - Internal Control Module Memory Error

Address 08:
Chassis Type: 6Y - Skoda Fabia
Controller: 6Y0 820 045
Component: Klimaanlage X0740
65535 - Internal Control Module Memory Error

Address 08:    
Chassis Type: 6Y - Skoda Fabia
Controller: 5J0 820 045
Component: Klimaanlage  X0850
65535 - Internal Control Module Memory Error

Address 08: Auto HVAC
Chassis Type: 6L - Seat Ibiza/Cordoba
Part No: 6L0 820 045 C
Component: Klimaanlage X00.8
65535 - Internal Control Module Memory Error

Address 08: Auto HVAC
Part No: 5J0 820 045
Chassis Type: Skoda Fabia 2
Component: Klimaanlage X0850
65535 - Internal Control Module Memory Error

Address 15: Airbags
Chassis Type: 9N - VW Polo
Part No: 1C0 909 605 K
Component: 18 AIRBAG VW51 0P 0010
Coding: 12600
Shop #: WSC 00788
65535 - Internal Control Module Memory Error

Address 15: Airbags
Chassis Type: 9N - VW Polo
Part No: 6Q0 909 601 F
Component: 05 AIRBAG VW5 0010
Coding: 12341
Shop #: WSC 31414
65535 - Internal Control Module Memory Error

Address 15: Airbags
Chassis Type: 6L - Seat Ibiza/Cordoba
Part No: 6Q0 909 601 F
Component: 01 AIRBAG VW5 0010
Coding: 12337
Shop #: WSC 06441
65535 - Internal Control Module Memory Error

Address 17: Instruments
Chassis Type: 8E - Audi A4 B6/B7
Part No: 8E0 920 900 HX
Component: KOMBI+WEGFAHRS. RB4 D27
Coding: 00142
Shop #: WSC 19411
65535 - Internal Control Module Memory Error

Address 37: Navigation
Part No: 3B0 919 887 D
Component: Navigation  BNO 0201
65535 - Internal Control Module Memory Error

Address 45: Inter. Monitor
Chassis Type: 6N -  VW Polo
Part No: 6N0 951 171
Component: Innenraumueberw. 0002
65535 - Internal Control Module Memory Error

Address 56: Radio
Part No: 1C0 035 157 C
Component: Radio DE2 0004
Coding: 00401
Shop #: WSC 00066
65535 - Internal Control Module Memory Error

Address 56: Radio
Part No: 1J0 035 180 B
Component: Radio DE2 0004
Coding: 01031
65535 - Internal Control Module Memory Error

Wednesday, July 22, 2015

EXCESSIVE COMMS ERRORS

EXCESSIVE COMMS ERRORS

Looking at the partial scans from several different vehicle platforms listed below, it is quite obvious to see that they all suffer from the same ailment commonly known as--Excessive Comm Errors--from Audi to SEAT, from VW to SKODA. Many VAG car owners have attached their own prefixes to it, like "vag com excessive comm errors", "vcds excessive comm errors", " note excessive comm errors", "vcds lite excessive comm errors", "auto hvac excessive comm errors", "address 08 excessive comm errors", but they all mean the same thing. It says that the scan tool could not communicate with said module because of some obstacle . Perhaps its conflicting with an after market Radio installation on Address 56 or  a combination of VCDS software/protocol/cable. The reason could also be that some other module on the network had been incorrectly configured (module coding) causing the scan tool to struggle to identify said module and after several times attempts fail (timeout) and presents a "Note: Excessive Comm Errors" and perhaps flag a 01044- control module incorrectly coded DTC as well.  However this isn't always the case, because it could also be caused by a setting on the scan tool software--flow control, start and stop bits, etc. The HVAC-address-08, ABS Address-03, Airbag Address-5 etc.. speak protocol KWP-1281 or protocol KWP-2000 and if the incorrect protocol has been selected, the  "Note: Excessive Comm Errors" does pops up. Some HVAC module will also generate a U0324  DTC  meaning that the scanner software is incompatible with the HVAC Control Module or the module concerned. If VCDS doesn't work, try the older VW Tool software or Commander 5,  which I have found has better HVAC and engine fan control settings than VCDS with a VAG-K-CAN cable or KKL-VAGCOM cable. I think the most common reason for excessive comm errors is using the incorrect interface cable because a KII-USB  (K2-USB) cable will not work on cars manufactured after 2005 and a Micro-CAN cable will only work on cars built prior to 1996. So it you have a later vehicle, get the right cable or invest in a Auto Boss V30 or a Launch X31 scan tool because they tend not give  Excessive Comm Errors that the VCDS software/protocol/cable combination is so notorious for. 


Address 01: Engine ---------------------
Chassis Type: 6K - Seat Ibiza / Cordoba
Controller: 6K0 906 032 AC
Component: ME7.5.10 4192
Coding: 00001
Shop #: WSC 06402
Note: Excessive Comm Errors

Address 01: Engine ---------------------
Chassis Type: 6L - Seat Ibiza/Cordoba
Note: Excessive Comm Errors

Address 01: Engine
Chassis Type: 70 (7D - VW Transporter)
Part No: 022 906 032 AF
Component: MOTRONIC ME7.1 G 0003
Coding: 00003
Shop #: WSC 27441
Note: Excessive Comm Errors


Address 02: Auto Trans
Chassis Type: 70 (7D - VW Transporter)
Part No: 01P 927 733 CG
Component: AG4 Getriebe 01P 4893
Coding: 00000
Shop #: WSC 00000
Note: Excessive Comm Errors

Address 03 ---------------------
Controller: 6Q0 907 379 L
Component: FRONT ABS MK60 0101
Coding: 0001097
Shop #: WSC 31414
Note: Excessive Comm Errors

Address 03: ABS Brakes
Chassis Type: 70 (7D - VW Transporter)
Part No: 7D0 614 111 B
Component: ABS/EDS 5.3 D00
Shop #: BB 24258
Note: Excessive Comm Errors

Address 08 ---------------------
Chassis Type: 1M - Seat Leon/Toledo
Controller: 1M0 820 043 D
Note: Excessive Comm Errors
Skipping Address 15-Airbags

Address 08 --------------------
Chassis Type: 4B - Audi A6 C5
Controller: 4B0 820 043 P
Coding: 00063
Shop #: WSC 02325
Note: Excessive Comm Errors

Address 08 --------------------
Chassis Type: 1M - Seat Leon/Toledo
Controller: 1M0 820 043 E
Component: 1M-CLIMATRON
Coding: 00043
Shop #: WSC 06402
Note: Excessive Comm Errors

Address 08: Auto HVAC
Chassis Type: 8D - Audi A4 B5
Controller: 8L0 820 043 D
Component: A4 KLIMAVOLLAUTOMAT_D75
Coding: 04144
Shop #: WSC 06325
Note: Excessive Comm Errors

Address 08 --------------------
Chassis Type: 1M - Seat Leon/Toledo
Controller: 1M0 820 043 D
Component: 1M-CLIMATRONIC X0605
Coding: 00043
Shop #: WSC 06441
Note: Excessive Comm Errors

Address 09: Cent. Elect. -----------
Chassis Type: 9N - VW Polo
Part No: 6Q1 937 049 D
Component: 0000 BN-SG. 1S34
Coding: 00012
Shop #: WSC 06402
Note: Excessive Comm Errors

Address 09: Cent. Elect.  -----------
Part No: 6Q1 937 049 D
Component: 00BP BN-SG. 1S34
Coding: 09358
Shop #: WSC 31414
Note: Excessive Comm Errors

Address 15: Airbags ------------------
Chassis Type: 6Y - Skoda Fabia I
Controller:
Note: Excessive Comm Errors

Address 15: Airbags
Chassis Type: 70 (7D - VW Transporter)
Part No: 1J0 909 603 BM
Component: AIRBAG VW3 - V04
Coding: 16973
Shop #: WSC 02743

Note: Excessive Comm Errors

Address 17: Instruments  -------------
Part No: 6L0 920 801 A
Component: KOMBI+WEGFAHRSP VDO V13
Coding: 00145
Shop #: WSC 00000
Note: Excessive Comm Errors

Address 17: Instruments ---------------
Chassis Type: 6L - Seat Ibiza/Cordoba
Part No: 6L0 920 801 A
Component: KOMBI+WEGFAHRSP VDO V13
Coding: 00145
Shop #: WSC 00000
Note: Excessive Comm Errors

Address 17: Instruments
Chassis Type: 70 (7D - VW Transporter)
Part No: 7D0 920 902 T
Component: T4-KOMBIINSTR. VDO V01
Coding: 03235
Shop #: WSC 02743
Note: Excessive Comm Errors

Address 19: CAN Gateway ---------------
Chassis Type: 6L - Seat Ibiza/Cordoba
Note: Excessive Comm Errors

Address 19: CAN Gateway
Chassis Type: 70 (7D - VW Transporter)
Part No: 6N0 909 901
Component: Gateway K<->CAN 0001
Coding: 00001
Shop #: WSC 02743
Note: Excessive Comm Errors

Address 25: Immobilizer  --------------
Chassis Type: 9N - VW Polo
Note: Excessive Comm Errors

Address 25: Immobilizer
Chassis Type: 70 (7D - VW Transporter)
Part No: 6X0 953 257
Component: IMMO 0008
Coding: 00001
Shop #: WSC 20309
Note: Excessive Comm Errors

Address 35: Centr. Locks
Chassis Type: 70 (7D - VW Transporter)
Part No: 7D0 959 800 C
Component: Funksteuergerát 0001
Coding: 00001
Shop #: WSC 02743
Note: Excessive Comm Errors

Address 44: Steering Assist ------------
Chassis Type: 6Y - Skoda Fabia I
VCID: 55AA04A28569
Note: Excessive Comm Errors

Address 56: Radio ---------------------
Chassis Type: 17 - VW Golf Citi
Controller: 17S 035 186
Note: Excessive Comm Errors

Address 7E: Ctrl Head Dash -------------
Chassis Type Audi TT
Protocol: KWP2000
Controller:
Note: Excessive Comm Errors


Thursday, June 11, 2015

AUDI EPC LIGHT PROBLEMS


AUDI EPC LIGHT

It is common knowledge that EPC light problems have been haunting Audi drivers incessantly for the past few years, announcing itself on Audi A1, Audi A2, Audi A3, Audi A4, Audi A5, Audi A6, Audi A7, Audi A8, Audi Q3, Audi Q5, Audi Q7, the Audi RS4, Audi RS6, Audi RS8, Audi R8, Audi S4, Audi S6, Audi S8 and Audi  TTs even before they're run-in. Several Audi owners are dismayed that EPC problems present themselves on virtually new cars. In fact, EPC problems pop-up at any time, on any Audi new or old fitted with X-by-Wire technology. Any Audi  without a throttle cable, is naturally fitted with a full Drive-by-Wire system which is supervised by the Electronic Control Circuit (EPC)  / Electronic Throttle Control (ETC)  that turns on the dashboard mounted EPC (K132) indicator light when it detects a malfunction, then registers Diagnostic Trouble Codes (DTC)  in the ECM memory.  Even though the EPC light turns on exclusively for  non-emission related faults, it does however turn on along with the MIL for emission related faults. The EPC  / ETC is a torque monitoring circuit and monitors for torque discrepancies and torque inefficiencies and when it detects one, sends the vehicle into emergency running mode (limp mode). These are prevalent when towing, when driving up an incline, when in manual mode, when in cruise control, after spirited driving, etc, and may even cause the ABS, ESP   lights to came on. Some drivers, assume  that it's happening more frequently over time and others are concerned that the EPC trouble are going to get worse because of its  randomness. But this is not the case. Bear in mind that once the EPC light is on, no other EPC related fault is going to make it glow any brighter. Once it's on, it's stays on even if the battery is disconnected, and it will come back on when you reconnect. However, the ECU will monitor the EPC circuit and if the same error does not occur in three successive trips of at least 7 kilometers, it will erase the DTC and it would seem as if it never happened, until the next time.  These are safely features specific to Drive by Wire systems and their workings can be viewed in the adaptation groups when retrieving errors with a scan tool.

ADAPTATION GROUPS PERTAINING TO EPC

Group 60 -- Throttle Valve Adjuster / Adaptation Epc-system
Group 61 -- Epc-system / Throttle Valve Adjuster (System 1) 
Group 62 -- Epc-system / Throttle Valve Adjuster (System 2)
Group 63 -- Kickdown Function
Group 66 -- Cruise Control Status

AUDI EPC LIGHT RELATED DTC

18039 / P1631 - Accelerator Position Sensor (G79): Signal too High 
18041 / P1633 - Accelerator Position Sensor 2 (G185) Signal too Low
18042 / P1634 - Accelerator Position Sensor 2 (G185): Signal too High
18047 / P1639 - Accelerator Position Sensor 1/2 (G79/G185): Implausible Signal 
 00777 - Accelerator Position Sensor (G79): Implausible Signal

No response from the throttle even with your foot flat on the accelerator pedal.. There are two potentiometers fitted to the accelerator pedal which are monitored by the ECU and when it it detects an intermittent signal from one pot, it turns on the EPC light then uses the second pot for acceleration but it is limited. When both pots detected as are intermittent, EPC light goes on and engine only runs at idle speed. When this error occurs, turn the engine off, stomp on the accelerator a few times through its full travel.  It could just be specks of dust that settled on the one of the potentiometer (variable resistors) tracks that stymied the ECU for a few millisecond or so. I this happens often and thereafter, presenting a 18047 / P1639 or 18039 / P1631 or 18042 / P1634 or 18041 / P1633 then consider replacing the accelerator pedal.

No response from the throttle even with your foot flat on the accelerator pedal. There are also two redundant potentiometers in the throttle body that determines the throttle valve angle and it has three modes of failure. One for when the valve angle sensor fails, one for when throttle valve actuator (motor) malfunctions and one for when throttle valve position is cannot be recognized by the ECU. When this happens  the ECU shuts off the voltage supply to the actuator, causing the throttle valve to defaults to mechanical stop position and the engine speed is limited to 1200 RPM. If any of the DTC fault below show up in your scan, check the 6 pin plug interfacing with the throttle bodyIt would be best to redo adaptation thereafter before thinking of replacing the throttle body. 

000289 / P0121- Throttle Position Sensor (G69): Implausible Signal - Intermittent
16506 / P0122 - Throttle Position Sensor (G69): Signal too Low - Intermittent
17987 / P1579 - Throttle Actuator (J338): Adaptation Not Started - Intermittent
17976 / P1568 - Throttle Actuator (J338): Mechanical Failure 
17972 / P1564 - Throttle Actuator (J338): Under-Voltage during Basic Setting 
17952 / P1544 - Angle Sensor 1 for Throttle Actuator (G187): Signal too Large - Intermittent
16606 / P0222 - Angle Sensor 2 for Throttle (G188): Signal Too Low - Intermittent
000547 / P0223 - Angle Sensor 2 for Throttle (G188):Signal Too High - Intermittent
17581 / P1173 -  Angle Sensor 2 for Throttle Actuator (G188) Signal too High 
18042 / P1634 - Accelerator Position Sensor 2 (G185): Signal too High 

You have difficulty starting but eventually does start but idles very rough, bucks and surges when you attempt to drive it. The   EPC, MIL (Check engine light)  and ESP lights come on. This is most likely caused by the Injectors  N30-N33 or the Ignition Coils N (1st cylinder), N128 (2nd cylinder), N158 (3rd cylinder) and N163 (4th cylinder) since both the Injectors and Ignition coils causes exactly the same symptoms. It also   exhibit the following DTCs.

17633 / P1225 - Fuel Injector for Cylinder 1 (N30): Short to Ground  - - Intermittent
17634 / P1226 - Fuel Injector for Cylinder 2 (N31): Short to Ground  - - Intermittent
17635 / P1227 - Fuel Injector for Cylinder 3 (N32): Short to Ground  - - Intermittent
17636 / P1228 - Fuel Injector for Cylinder 4 (N33): Short to Ground  - - Intermittent

MORE EPC PROBLEMS

J757 Engine Component Power Supply Relay cause loss of  high-pressure and turns on EPC. ESP and MIL lights.

N75 Solenoid valve for charge pressure limitation and turns on the  EPC and MIL lights but shown no symptoms of failure except go into limp mode. 


Audi A1, Audi A2, Audi A3, Audi A4, Audi A5, Audi A6, Audi A7, Audi A8, Audi Q3, Audi Q5, Audi Q7, the Audi RS4, Audi RS6, Audi RS8, Audi R8, Audi S4, Audi S6, Audi S8 and Audi  TTs EPC Problems.

Saturday, June 6, 2015

KNOCK SENSOR

VAG KNOCK SENSOR K1 AND THE EPC LIGHT

VW, Seat, Skoda  and Audi Knock sensors have become quite notorious for sending the car into "limp mode". Limp mode is a safety feature on all Drive by Wire vehicles, implying an EPC-electronic power control-but no accelerator cable. EPC implies torque control. By analogy,  its something like a horse that gets spooked and takes off at high speed and out of control with its rider unable to rein him in,  or a frayed accelerator cable that becomes stuck while driving at high speed. That's just a recipe for disaster. Imagine stepping on the brake pedal but the high revs of the engine just forces the car forward, smoke pouring from the brake pads to the point that the become glazed and  no longer has any effect. Pushing the transmission into neutral isn't an option because without the load, the engine is destined to blow, perhaps even push a piston  through the side of the engine lock.  Drive by wire prevents this from happening and cuts power to the powertrain if it detects a fault that puts the engine at risk. Knock reacts somewhat similar to backfire since both are due to detonation and pre-ignition-incomplete combustion.

Detonation is a common problem associated with lean fuel mixture -non stichometric-and torque. The EPC light is often triggered on an incline when the torque is insufficient to pull the car uphill when in an inappropriate gear. Knock sensors can detect combustion knocks in individual cylinders. Knock sensor 1 (G61) senses cylinders 1 & 2, and knock sensor 2 (G66) senses cylinders  3 & 4. To prevent combustion knock, the ECU cylinder selective knock control overrides the electronic control of the ignition timing by retarding the timing, but may not be unable to if the Fuel Octane is too low causing secondary combustion in the cylinder. Knock sensor 1 (G61) is known to trigger EPC light and activate limp mode, hence it needs to be checked for flush engine contact and correct torque. DTC  P0171 and P0174 could show up in scans.

The ECU calculates engine ignition timing based on input signals from Throttle Position (TP) Sensor G79 and  Accelerator Pedal Position G185, the  Engine Speed (RPM) Sensor G28,  the load signal from Mass Air Flow (MAF) Sensor G70, the signal from the Throttle Valve Control Module J338,  the Coolant Temperature (ECT) Sensor G62, both Knock Sensors G61, G66 (additional G198 & G199 on V6, W8 & W12 engines) and signals from Camshaft Position Sensors G40, G163, (additionally G300, G301 on V6, W8 & W12 engines) When the engine is below 40 degrees  celsius knock sensors signals are not used to make timing decisions. What this implies is that when the EPC light turns on  when the engine is still cold, the knock sensors are not guilty , neither  the the Mass Air Flow (MAF) Sensor G70 nor the Coolant Temperature (ECT) Sensor G62 since whilst idling, have nothing to do with torque. That leaves the Accelerator Pedal with G79 & G185, the Throttle  Control body senders G187 & G188,  the  Engine Speed Sensor G28,  Camshaft Position Sensors G40 & G163 as the EPC limp mode culprits. However sensors are fairly reliable but the wiring  harnesses  are  more likely to be the cause of the problem, see wiring in Audi.

Fuel pressure regulator valve N276, the wastegate bypass regulator valve N75 and the  Ignition Coil N, N128, N158, N163 and its Power Output Stage N122 are three  more EPC culprits. Injectors N30-N33 can also cause the EPC light to turn on and cause car to go into "limp mode" but also causes the engine not to run smoothly. Once again before condemning the sensors or actuators, check the wiring harnesses to them.



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The above EPC errors are common to Volkswagen, Audi, Skoda and Seat. The  VW, the 4motion, the Amarok, the new Beetle, the Bora, the Caddy, the Corrado, the CC, the Eos, the Fox, the Golf, the Jetta, the Kombi, the Lavida, the Lupo, the Passat, the Polo, the Phaeton, the Routan, the Santana the Scirocco, the Sharan, the Tiguan, the Touran, the Touareg, the Transporter, the Vento , the Up and lastly the Vivo. The Audi A1, A2, A3, A4, A5, A6, A7, A8, the Q3, Q5, Q7, the RS4, RS6, RS8, the R8, the S4, S6, S8, Audi TT. The  Seat Alhambra, the Altea, the Arosa, the Cordoba, the Ibiza, the Inca, the Leon, the Mii and the Toledo,  Skoda  Felicia, the Octavia, the Fabia, the Superb, the Roomster, the Yeti, the Rapid and the Citigo. The Audi RS-6, A4 Fsi, Audi A4, Audi S3, Audi TT, Audi R8, audi a4 2.8 quattro 5 speed, Skoda fabia, seat leon, seat ibiza, Avant RS 2, Coupé, Audi A3 Mk1, Volkswagen Golf Mk4, Volkswagen New Beetle, Volkswagen Bora/Jetta Mk4, SEAT León Mk1, SEAT Toledo Mk2, Škoda Octavia Mk1,  TFSI, FSI, GTI, TDI,