EPC light, no CEL, Limp mode

[WadeH]

Hi Guys,

My 2010 mk6 GTI DSG has ~67,000km on it and has recently started giving me grief. At seemingly random intervals it pops the EPC light, the engine starts shaking like it is running on 3 cylinders and has restricted revs like it is in a limp mode. It has happened when switching on hot or cold, or mid driving at any speed. It does not leave any codes at all to suggest that it has been playing up.

Some odd info - the fuel consumption reading drops to 0.0L/100km while the EPC light is on and sometimes the A/C gets disabled when this happens too, but either way, normally it clears itself after putting into neutral and giving it some revs.

So far we have done the following to no avail:
- 4x R8 coilpacks
- NGK Iridiums
- New throttle body (interestingly, did around 3000km without issue after this, but has since returned)
- New crank/speed sensor
- New coolant temp sensor
- Replaced something in PCV but can't remember what exactly.

When it is not playing up, it drives as good as ever, but definitely has me beat and hopefully someone has an idea of where to look next before I find a box of matches :evil:

Any help at all will be hugely appreciated!!

 

[11gti718]

Any carbon cleaning done before ? Possibly faulty injectors ?.. if you know anyone with vcds. Have them scan the car dor any codes. Any soft codes that wont trigger a CEL.

 

[WadeH]

No carbon cleaning done, would that cause such an intermittent 99% power loss and then go back to full strength?
It has been hooked up to VW's computer and they found a few dodgy looking outputs from the sensors which they thought may be the fault, but did not sort it out. No soft codes at all, which is what has my mechanic stumped, nothing seems to be recording that it is having a problem at all. It hasn't been scanned for the last 10+ of these EPC episodes, but presumably the same culprit behind all of them.

 

[11gti718]

What exactly do you mean by "dodgy looking outputs". Is it just EPC light flashing or stays lit ? No CEL ? Try geting a vagcom cable. That definitely helps.

 

[WadeH]

They said they were seeing some erratic readings coming from MAF, coolant and crank sensors, VW Germany advised that the crank sensor can influence the other readings so tackle that first. When the sensor was removed, it was physically cracked, so we chalked that up as a win and it was fine for several weeks after.
The EPC light comes on and stays on while it is having it's moment, then vanishes as soon as it clicks back in to being happy. No CEL, just the "Engine Fault Workshop!" on the MFD. Again, that vanishes as soon as it stops spluttering and leaves no trace.

 

[jemartti]

My car is going through very similar pains to yours and I'm also lost as to what to do next.

Mine is a 2009 GTI mkv (TSI), 120k miles. It's popping an EPC light + Check Engine Workshop + limp mode quite frequently when I start the car; it also happens a few minutes into my drive sometimes. I'll turn the car off and on a few times and it'll usually go away until the next day. No codes are being stored. I also got the Throttle Body replaced, and that also solved the problem for a few thousand kilometres.

Did you try replacing the Throttle Body wiring harness? There's a TSB out for the wiring, here's a link Arin@APR posted in the mkv forums a while back. Even though my throttle body was replaced, I'm suspicious about the wiring. I'm not sure if the new throttle body wiring harness had the updated connector, and I don't see any splices on my harness indicating the new one has been spliced in.

Maybe try unplugging, cleaning, and replugging in your Throttle Body connector and see if that temporarily clears it up? I can usually get a clean startup with no codes after doing that but it doesn't last long so it might be a red herring. In any case, I'm going to try installing the (spendy) updated kit (ECS tuning has it). I just ordered the kit last night so I'll keep you posted.

 

[jettaglis]

They said they were seeing some erratic readings coming from MAF, coolant and crank sensors, VW Germany advised that the crank sensor can influence the other readings so tackle that first. When the sensor was removed, it was physically cracked, so we chalked that up as a win and it was fine for several weeks after.
The EPC light comes on and stays on while it is having it's moment, then vanishes as soon as it clicks back in to being happy. No CEL, just the "Engine Fault Workshop!" on the MFD. Again, that vanishes as soon as it stops spluttering and leaves no trace.

If the crank sensor was over torqued it could still be your culprit. Get some freeze frame data if possible.

 

[FriggenT1]

My car is going through very similar pains to yours and I'm also lost as to what to do next.

Mine is a 2009 GTI mkv (TSI), 120k miles. It's popping an EPC light + Check Engine Workshop + limp mode quite frequently when I start the car; it also happens a few minutes into my drive sometimes. I'll turn the car off and on a few times and it'll usually go away until the next day. No codes are being stored. I also got the Throttle Body replaced, and that also solved the problem for a few thousand kilometres.

Did you try replacing the Throttle Body wiring harness? There's a TSB out for the wiring, here's a link Arin@APR posted in the mkv forums a while back. Even though my throttle body was replaced, I'm suspicious about the wiring. I'm not sure if the new throttle body wiring harness had the updated connector, and I don't see any splices on my harness indicating the new one has been spliced in.

Maybe try unplugging, cleaning, and replugging in your Throttle Body connector and see if that temporarily clears it up? I can usually get a clean startup with no codes after doing that but it doesn't last long so it might be a red herring. In any case, I'm going to try installing the (spendy) updated kit (ECS tuning has it). I just ordered the kit last night so I'll keep you posted.

Have you had carbon cleaning done? 120k miles I would assume so?

 

[GIACUser]

Not sure if this is of any help. Copy and Paste from article on line.

Reasons Why EPC Dashboard Warning Light Is On
fixing the VW epc warning lightThough we recommend simply scheduling an appointment for service with us online, if you’re someone who likes to handle their fixes at home, here are a few possible causes for the EPC light turning on.

Engine speed sensor: Some drivers have reported that the solution to getting the EPC light to go away was as simple as replacing an engine speed sensor. If the engine dies off while driving, you may want to look into this.

 

[WadeH]

The TSB for the throttlebody harness was for mkV though yeah? I was under the impression they fixed it for the mkVI? I will see if they still have the data saved, but I doubt it. The frustrating part is that they can get to look at it til the new year now. Might see if I can get my hands on a OBDEleven so I can keep tabs on it myself.

 

[WadeH]

Update:
So it had miraculously healed itself over Christmas, but just repeated the same again this evening on the way home. I had my OBDeleven plugged in and it gave me a P2146 - Fuel injector group "A" supply voltage circuit open. I guess that's my next direction, but has anyone had a similar experience? I'm assuming a bad connection/crimped wire somewhere?

 

[Deangolfgti]

Mate

Hi Guys,

My 2010 mk6 GTI DSG has ~67,000km on it and has recently started giving me grief. At seemingly random intervals it pops the EPC light, the engine starts shaking like it is running on 3 cylinders and has restricted revs like it is in a limp mode. It has happened when switching on hot or cold, or mid driving at any speed. It does not leave any codes at all to suggest that it has been playing up.

Some odd info - the fuel consumption reading drops to 0.0L/100km while the EPC light is on and sometimes the A/C gets disabled when this happens too, but either way, normally it clears itself after putting into neutral and giving it some revs.

So far we have done the following to no avail:
- 4x R8 coilpacks
- NGK Iridiums
- New throttle body (interestingly, did around 3000km without issue after this, but has since returned)
- New crank/speed sensor
- New coolant temp sensor
- Replaced something in PCV but can't remember what exactly.

When it is not playing up, it drives as good as ever, but definitely has me beat and hopefully someone has an idea of where to look next before I find a box of matches :evil:

Any help at all will be hugely appreciated!!

u have the exact same problem as me i just paid 6k for the car and had it 2 days ive changed the same things as you apart from coilpacks and im still in the same situation ive had it in 3 garages and they all say they havnt got a clue

 

[BudgetPhoenix]

you might have a short in the fuel injector wiring harness or a bad injector itself with p2146