# S3 EPC Light...?



## vasgolfr (Jul 23, 2014)

This past weekend my new S3 had a problem with throttle response (car would barely accelerate and the engine ran rough) and the EPC warning light came on. Then when I turned the car off and on again, the warning light went off and the problem went away. All the owner's manual says is when the EPC warning light comes on, bring the car to Audi for evaluation...

Audi now has my car for evaluation... anyone know what's up with the EPC light going on at only 3600 miles??

Thanx.

Victor


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## turbo slc 2.9l (Dec 4, 2003)

My S3 did the same thing around 1500miles.. Took it to the dealer & they scanned, found misfires in multiple cylinders.. They tried saying I either had bad gas or low gas when it happened.. ( tank was 3/4 full of 93 octane so who knows).

They have record of it & sent me on my way, hasn't happened again since. My car still has a valid warranty so I'm not too concerned. I posted about it a few months ago but I don't recall getting much input regarding the problem


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## vasgolfr (Jul 23, 2014)

turbo slc 2.9l said:


> My S3 did the same thing around 1500miles.. Took it to the dealer & they scanned, found misfires in multiple cylinders.. They tried saying I either had bad gas or low gas when it happened.. ( tank was 3/4 full of 93 octane so who knows).
> 
> They have record of it & sent me on my way, hasn't happened again since. My car still has a valid warranty so I'm not too concerned. I posted about it a few months ago but I don't recall getting much input regarding the problem


Thanx for the info.

I haven't yet heard from my dealer today so I don't know if they've even analyzed the problem. However, in trying to use some common sense regarding what you've noted above... perhaps when the cars leave the factory, various sensors are set at a default parameters or thresholds, and fuel sensors for example may react differently with different fuel blends in different part of the country...?? Maybe (due to an odd fuel blend... "bad gas") the system software had to reset a fuel sensor parameter or threshold???

Maybe (hopefully) the answer turns out to be something that simple... Just guessing.


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## Vermilion (Aug 25, 2010)

Mine came on the other day after I had just installed my APR intake. Funny thing is it didn't run rough or anything, just the EPC light was on. Took the intake off and put the stock back on and it ran fine. I have since put the APR back on and cruised around to let the ECU "learn" the new intake and everything seems fine.


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## evilboostedeagle (Jul 9, 2007)

There's a new ECM update out for S3. "EPC light on after vehicle reads false misfires" Dealer will most likely update your ECM software to the latest version "002".


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## soulflyer (Feb 18, 2012)

been there... done that:

http://forums.vwvortex.com/showthre...r-codes-P130A-P03AF-P0726&highlight=soulflyer


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## evilboostedeagle (Jul 9, 2007)

soulflyer said:


> been there... done that:
> 
> http://forums.vwvortex.com/showthre...r-codes-P130A-P03AF-P0726&highlight=soulflyer


This ECM update was released the end of July. Just a week or so ago.


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## soulflyer (Feb 18, 2012)

evilboostedeagle said:


> This ECM update was released the end of July. Just a week or so ago.


yep, you are right. And looking back the ECM update would have probably fixed the issue. But they decided to replace the knock sensor and no complaints for the last 7000km...


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## vasgolfr (Jul 23, 2014)

*Audi Dealer's evaluation...*

My Audi dealer reviewed the error logs on my S3 and found that cylinders 1 and 3 had misfiring issues triggering the EPC light and the engine hiccup... No clear cause was identified although the Audi service manager stated that fuel source issues (inferior quality premium gas) has been suspected in causing this type of problem. I don't necessarily believe the service manager's comment to be valid because there's no proof determining that premium fuel purchased at Sam's (for example) will be any more problematic to my engine than fuel bought at a Shell, Texaco, Chevron, etc. gas station...

I will however make note of my fuel source if the engine has further problems and the EPC light comes on again.

The dealer really didn't do anything to "fix" the problem except to clear the error logs and reboot the software... My car is running very good as expected.


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## turbo slc 2.9l (Dec 4, 2003)

vasgolfr said:


> My Audi dealer reviewed the error logs on my S3 and found that cylinders 1 and 3 had misfiring issues triggering the EPC light and the engine hiccup... No clear cause was identified although the Audi service manager stated that fuel source issues (inferior quality premium gas) has been suspected in causing this type of problem. I don't necessarily believe the service manager's comment to be valid because there's no proof determining that premium fuel purchased at Sam's (for example) will be any more problematic to my engine than fuel bought at a Shell, Texaco, Chevron, etc. gas station...
> 
> I will however make note of my fuel source if the engine has further problems and the EPC light comes on again.
> 
> The dealer really didn't do anything to "fix" the problem except to clear the error logs and reboot the software... My car is running very good as expected.


That's pretty much the same situation that happened when I was experiencing the same issue, no real fix from the dealer just clear codes..
I agree about your statement regarding fuel from location to location.. but to be sure I've been using fuel from Shell since my light came on, with exception of 2 tanks from Sunoco when there was no Shell stations around, and things have been good so far at roughly 5k miles on the clock.

Good luck with your S3!


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## Spoooolin (Mar 31, 2015)

If we do not verify the complaint, and have it act up currently anything we do to attempt to fix your complaint is a total educated guess. I would like to assume they know about the TSB that just came out about the updated ecm logic....But they they know what they say when you assume things...


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## dgamez96 (Sep 7, 2015)

*S3 EPC light*

what does the dealershio told you? did they scan your car? ... y had the same problem  in my s3 8p I press full throttle and the car didn't advance! then i restar the car and the epc light was off. I don't know why the car did that.


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