EPC + ESP + Limp Mode

[The_Coat]

Hi All,

Wonder if anyone can give me some help....

Today while coming off the motorway after 60 miles the EPC light came on followed by the ESP light and the car went into limp mode. I pulled over and turned engine off and back on again and the two lights had gone out and the car was back to normal power. I drove it back 60 miles with no issues.

Was just doing normal driving at around 60/70mph with the cruise control on, which is the first time I have used this on the car since I’ve owned it.

I do not have Vagcom to check the error but looking at previous posts on here someone has mentioned the lambda sensor could be at fault while some info on the web points to a faulty speed sensor?

For now I will see how the car goes before getting anyone to look at it but does anyone have any idea what could be at fault?

Cheers

[klauster]

sounds like a coil pack....

[The_Coat]

sounds like a coil pack....

Thanks, can you tell with one needs to be replaced if it is this? I gusss VAGCOM is needed.

Looking at the history the coil pack recall (2E8E9?) was done in September last year at 19.5K, the car has now done 21.5K.

Cheers

[Madmonkee]

AFM? This again (ref vauxhall) used to be the tell tale sign the meter had gone on the Zlet,ZLeh engines.
MAF/AFM

[rs4lee]

Get the car scanned ... Epc and traction light can come on for a number of faults ... No point in second guessing !!

[adsgreen]

Maf sensor too...
Get it scanned as it should still have a record of the log.

[The_Coat]

Thanks for the input guys, will hopefully be getting it scanned next weekend at a friend’s garage.

Cheers

[Coaster]

I had something similar on Friday evening. I was just cruising when the EPC and ESP (traction) Lights both came on amber at the same time and the car seemed to be in limp mode. Drove to my destination, switched off and back on and all was fine. I called Audi Assist and the fault seems to have been P2138 throttle/pedal position sensor, switch voltage correlation pending. Anyway, it's been fine since so have done nothing about it. Giving it a good pasting often seems to clear these issues.

[adsgreen]

I don't know the specifics of the rs4 pedal sensor but most of the ones I've seen have two sensors set out of phase.
Ie One measuring 0 at closed and 1 and wide open throttle. The other is identical but measures 1 at less and 0 at wide open throttle.
The idea is that for all pedal positions the sum total of both sensors is always 1. So it acts like a simple checksum to make sure both sensors are working properly and that the reading for pedal position is accurate.
This code can be thrown when the total is outside tolerance and will generally put any car into limp home mode (hardly surprising if the car can't trust the pedal position!)
See if it comes back but if it does I would expect a new pedal sensor and on other cars they are it cheap.

I would expect pedal position values are monitorable by VCDS

[The_Coat]

Car has been fine since and never did get it scanned. Also not used the cruise control since that day

[sakimano]

sounds like a coil pack....

Really? Wouldn't he have some oretty violent misfires and an intermittently flashing check engine light?

[adsgreen]

sounds like a coil pack....

Really? Wouldn't he have some oretty violent misfires and an intermittently flashing check engine light?

'Depends'
The misfire detection system is based on measuring crank acceleration. The Ecu is expecting to see 8 evenly distributed acceleration spikes broadly the same (this is how it know what cylinder is missing as it know what one should be firing at any given time). Because of this it can only check under quite restricted circumstances - ie speed is relatively constant for example.
If there are a few 'misses' in a given timeframe (30 secs say) then you will get a check engine light.
If there are a large number of persistent misses in a very small time window (10secs say) ten you'll get the flashing e fine light an limp home mode (mainly due to excess fuel in the exhaust can overheat the cat).

So it's very possible to have a dying cool pack cause enough misses to trip the light but not enough to trip flashing light

[Coaster]

sounds like a coil pack....

Really? Wouldn't he have some oretty violent misfires and an intermittently flashing check engine light?

'Depends'
The misfire detection system is based on measuring crank acceleration. The Ecu is expecting to see 8 evenly distributed acceleration spikes broadly the same (this is how it know what cylinder is missing as it know what one should be firing at any given time). Because of this it can only check under quite restricted circumstances - ie speed is relatively constant for example.
If there are a few 'misses' in a given timeframe (30 secs say) then you will get a check engine light.
If there are a large number of persistent misses in a very small time window (10secs say) ten you'll get the flashing e fine light an limp home mode (mainly due to excess fuel in the exhaust can overheat the cat).

So it's very possible to have a dying cool pack cause enough misses to trip the light but not enough to trip flashing light

adsgreen; please ditch the iPad, it's making you appear illiterate to those who don't know how knowledgable you are.
The symptoms described above as experienced by both the OP and me could not have been a coil pack.

[adsgreen]

jesus - I didn't notice how bad auto correct had got it <sigh>

As for my comment, it was more in answer to saki's point that coil pack failures only ever cause flashing mil and heavy misfire. not always the case.
I agree I don't think in this case it would be coil pack as you wouldn't expect the ESP light on as well.

[usedcar]

fyi esp uses the mass for engine load and your epc also. so could be a combo of coil, loose spark plug (seen that) and mass failing or dirty.