VW ELECTRONIC POWER

EPC LIGHT EXPLAINED

As I mentioned before in my older blogs, the new generation of VW cars are designed to turn on an EPC Light (not check engine light) so that only the  Volkswagen dealership service technician or technicians are supposed to do any an all servicing and repairs.  The VW workshop manuals specifically discourages anyone other than a qualified or trained mechanics / auto-electrician and automotive technician to perform servicing, especially changing codes and performing readiness test.  This is because  incorrectly set readiness and adaptation settings can completely disable your car and virtually render it useless. To repair it would then cost a small fortune.

CHECK ENGINE LIGHT

An earlier blog, covers some late model VAG cars with fuel injection and electronically controlled throttle body instead of the traditional accelerator cable controlling the throttle valve. It is called Drive-by-wire or DBW for short. When the Engine Control Unit -ECU, which invariable is a computer in its own right detects a fault  Diagnostic Trouble Code - DTC  in the Drive-by-wire system, it registers a fault Diagnostic Trouble Code - DTC in its non volatile memory and turns on the EPC light, disables the accelerator and throttle body, limit the engine to a maximum of 1500 rpm -"Limp Mode".  This would be sufficient power to "Limp Mode" the car to a service centre without causing further damage to the car or unduly polluting the air should the fault cause it to smoke. This is a safety precaution and can be equated with, what would happen if  an accelerator cable got stuck in the downward position. Disaster could follow. The Engine Control Unit -ECU collects faults Diagnostic Trouble Code - DTC from all senders and stores an internal list, which is only visible with a diagnostic tester. Diagnostic Trouble Code - DTC can range from excessive emissions to - intermittent air bag connections, from brake light failure to - depleted brake pads, from interior ultrasonic failure to - immobilizer problems to even disconnecting the battery. Each of these faults generates codes, some of which can be viewed in future blogs.

Should the Volkswagen Engine Control Unit -ECU  considered a Diagnostic Trouble Code - DTC to be so serious that it could possibly do harm to the engine or the environment, it will inhibit the throttle function and limit the engine revs or even disable starting or idling completely.  Unfortunately the only way to repair such problems, is to connect the  Volkswagen Golf,  Jetta, VW Polo, or Volkswagen Beetle, to a dignostic tester through its CAN-Bus / OBD2 / OBDII port and view  Diagnostic Trouble Code - DTC  if any and  Diagnostic Trouble Codes, clear them from memory and perform corrective procedures.  Below is an overview of the Electronic Power Control Circuit - EPC and how the Drive-by-wire system operates.

The basic operation of  the Electronic Power Control (EPC) Schematic showing inputs
from drive-train sensors and output signals to drive-train actuators.

Other INput senders could result in similar problems. For example - the Oxygen Sensor could detect that the exhaust fumes carbon mixture exceeds the prescribed level which is toxic to  the atmosphere and the environment. It could disable driving of the vehicle by enabling the Electronic Power Control Circuit - (EPC), turning on the EPC warning light or even disable starting not allowing the car to idle. This could be due to a dead plug causing the idling to be erratic and not burning up all the fuel. This un-burnt fuel will invariably change the exhaust fumes composition which triggered the Catalytic Converter and Oxygen Sensor in the first place.

Like wise, when the brake light bulbs blow or the fuse to the brake circuit blows, an INput signal from the brake light sender could also activate the Electronic Power Control Circuit - (EPC), turning on the EPC warning light causing the car to go into "Limp Mode" because driving a car on a public road without brake lights is an accident just waiting to happen. In fact the Engine Control Unit (ECU) looks upon this car as non-roadworthy as a safety procedure. In a previous blog I described an Electronic Power Control Circuit - (EPC), which switches on the EPC light problem caused by an INput  signal from one of the knock sensors with the same results as above. Other senders INputs that can cause similar problems are:-

The Engine Speed Sender G28 situated at the flywheel.
The Hall Sender G40 situated at camshaft pulley
The Hot Air Mass Meter G70 and intake Air Temperature sender G42 situated near intake manifold.
The Lambda probe G130 situated upstream of catalytic converter
The Lambda probe G39  before catalyst converter
The Knock sensor I - G61 below intake manifold
The Knock sensor II - G66 below intake manifold
The Accelerator Position Senders G79 and G185 embedded in accelerator pedal (EPC Problem)
The Clutch pedal switch F36 situated in the drivers foot well.
The Brake light switch F and brake light switch F47 situated in the drivers foot well.
The Throttle control valve / motor drive assembly  J338 
The Angle Senders  G187 and G188 situated inside throttle body.
The Fuel Pressure Sender -G247

NB! VAG car owners who found this site to be helpful 

were interested in the following sites as well.

expowp, epc warning light, service engine light, photojani, service engine light on, service engine light on,  controversy365, check engine light service, epc car light, epc in car, nerdytoys, epc light on car, what is epc on a car,  lovelifelovehealth, check engine codes, check engine light codes, sightsofcapetown, what does epc mean, what does epc mean in a car,  sowpbox, what does epc mean on a car, check engine light,  electroniques, check engine light flashing, check engine light on,  blogspot-at, blinking check engine light, flashing check engine light,  photo-magix, service engine soon, service engine soon light,  godssites,  what does check engine light mean,  glycomix,  arth-ritis,  forex-bid,  foodsofthecape, engine warning light, languagesbarrier,   yellow engine light,  pimpyocar, what does the check engine light mean,  e-gimos.

MAKE REAL MONEY ONLINE WITH FOREX

LIMP MODE

LIMP MODE HOME / VW LIMP MODE

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

FIRST CASE / VW LIMP MODE

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

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

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

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

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

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

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

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

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

_______________________________________________

SECOND CASE  / VW LIMP MODE

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

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

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

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

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

Readiness: 0000 0101

EXPLANATION

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

_______________________________________________

THIRD CASE  / VW LIMP MODE

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

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

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

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

Readiness: N/A

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

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

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

_______________________________________________

FOURTH CASE  / VW LIMP MODE

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

VW ABS CODING

VOLKSWAGEN ABS DIAGNOSTICS

Using a code reader or  diagnostic tester to view your VW Polo ECU data is quite a treat and is also really cool. A view of the data just exudes the growth of motor vehicle technology in general and it is quite humbling if you are electronically minded and quite intimidating if you are mechanically minded.  However there is often the temptation to change a number or something, just to see what happens to your Volkswagen. If you are one of those people who just did that, I bet you have a wistful regret, wishing that you never did so in the first place because you got yourself a "01044 control module incorrectly coded error." Or perhaps you  swapped a 1996 VR6 engine into a 2007 MkV GTI chassis and got a "01044 control module incorrectly coded error." Or you had your car serviced and the ABS and ESP light stays on in the instrument panel and showing up as a "01044 control module incorrectly coded error."  Or you cleared that nagging airbag light on your VW Beetle, only to get a "01044 control module incorrectly coded error."

Control modules codings are normally NOT interchangeable since virtually every model among the numerous versions of  VW's  each have a different ABS/ESP module, Power Assisted Steerin Module, Climate control Module,  Instrument Module, Immobilizer Module and Engine Control Module and so many other modules. Taking this into consideration,  it is more than  obvious that one should NEVER copy coding from a different model VW, AUDI, SKODA or SEAT and paste it into your own Volkswagen, AUDI, SKODA or SEAT, unless you write down your original modules original coding so that you can revert back to it later, should things appear to go pear shaped. 

However if the two VW, AUDI, SKODA, or SEAT are the same in every respect, then  their module codings will be identical and therefore perfectly fine to use. Be particular about the module suffix since different suffixes signify different software versions which may not be compatible to your VAG car. Virtually each module that appears identical but has different letter suffixes will invariable have a different coding. So the rule is same car, same module, same module number, same module suffice, same coding. Disregarding this could incapacitate your car and cost you a huge amount of money.

Every Control module coding is stored as an onboard binary number, which in essence is the binary sum of the features for that specific module. Whereas the ECU also stores an onboard binary number which is the binary sum of all the Control Modules fitted in the car. This binary sum is called the checksum and any incorrectly coded  module will result in an erroneous checksum. If this is the case, the erroneous checksum is compared to a reference checksum also stored in the ECU module and any discrepancy could incapacitate your Volkswagen completely or present you with some peculiarities and error codes to match. Like the notorius 01044 control module incorrectly coded.  Checksum verification was adopted by BOSCH Motronic ECUs to validate its EPROM's stored data. Having said that, it is wise not to change the coding or replace any control modules in your VW AUDI, SKODA or SEAT unless you are au fait with binary and hexadecimal number systems. 

Below, is a list of VW ABS controllers and their respective coding which vary from  'ABS FRONT MK60 0101' to  'ABS 8.0 front H03 0002' to 'ABS 8.0 front H05 0002' to 'ABS 5.7 FRONT V20' to 'ABS 5.7 FRONT V30 ' to 'ABS/ASR 5.7 FRONT V20' to 'ABS 5.7 FRONT V00' to 'ESP 8.0 front H03 0001' to 'MABS 8.0 front  H04 0002' to 'ESP 8.0 front H03 0001' to 'ABS 8.0 front H03 0002' to mention but a few. Several VW, AUDI, SKODA and SEAT owners and mechanics are constantly searching the Internet for ABS module coding and hopefully this information may help them to get their Volkswagens, Skodas, Seats,  Audis and other VAG cars up and running once again.

VW POLO 6Q0 907 379 AC ABS Pump

VW Polo 9N
Address 03: ABS Brakes
Controller: 6Q0 907 379 AC
Component: ABS 8.0 front H03 0002
Coding: 0000145

ALTERNATIVE ABS MODULE CODING
NB! These are the codings I currently have but are certainly not the only ones use by Volkswagen, SEAT, Skoda and Audi. As I get them I will update this list.

6Q0 907 379    - Coding:  00036 or 00044
6Q0 907 379 AA - Coding: 0000005 or 0000008
6Q0 907 379 AB - Coding: 0000005 or 0000008
6Q0 907 379 AC - Coding: 0000145 or 0000142

6Q0 907 379 AF - Coding: 0002061 or 0002079 or 0002082 or 0002085 or 0002103 or 0002115 or 0002118 or 0002122 or 0002136 or 0002145 or 0002175 or 0002181 or 0002190 or 0002193 or 0002199 or 0002202
As can be seen above, AF suffix has the whole gamut of codings and each should be tried before throwing in the towel.

6Q0 907 379 AG - Coding: 0002202 or 0002229 or 0002238
6Q0 907 379 AH - Coding: 0000299 or 0000284
6Q0 907 379 AQ - Coding: 0002356
6Q0 907 379 AS - Coding: 0002347 or 0002368 or 0002368 or 0002491
6Q0 907 379 AT - Coding: 0000269
6Q0 907 379 BC - Coding: 0002136 or 0002098
6Q0 907 379 C  - Coding: 00044
6Q0 907 379 D  - Coding: 00124 or 00188
6Q0 907 379 E  - Coding: 0001097
6Q0 907 379 G  - Coding: 00044 or 00045
6Q0 907 379 H  - Coding: 00188
6Q0 907 379 L  - Coding: 0001097
6Q0 907 379 M  - Coding: 0000000
6Q0 907 379 R  - Coding: 0000008
6Q0 907 379 T  - Coding: 0000281 or 0000296 or 0000299

Make some quick money

Eat as much as you like at Alfonso's Wedding

A Classic Wedding Cake 

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.