Vag-Com Codes help // EPC ESP Limp Mode

A6 All/ S6 All
#1

Hi guys,

This morning after being stuck in some stop&go traffic for about 20mins, I turned off onto my street, pressed on the accelerator, and the car went into limp mode. ESP Fault message, EPC light. Your standard no power and max 40km/h. When stopped, the idle went from normal to really rough, back to normal, repeat.

Shut off the car, turned it back on. Faults persist (even when just in acc, no engine running). Tried that a few times. Then left the car off for 20 mins or so, back on, and she’s back to normal.

Now, this has happened to many people - including some of my friends, and normally it has been cured by coilpacks, though all the codes point to throttle body. I have the coilpacks in stock, and I will try them shortly. But I thought some of these codes may be curious, and I thought I would also post all this for posterity.

I made it home later in the day, although the car did beep at me for half a second at one point - just long enough for me to see “ESP Fault!” Then it disappeared and car continued as normal.

I scanned the car when I got home, and found the following. Some codes I couldn’t find on Ross-Tech - any idea? I have only a SuperVAG handheld reader.

289 ??? Anyone?
545 Angle Sensor for Throttle (G188): Implausible Signal
1056 Catalyst, Bank 1, Efficiency Below Threshold
5445 Throttle Valve Controller: Malfunction
5480 ???
5497 Throttle Actuator (J338): Adaptation Not Started
5715 Please Check Memory of ABS Controller
8454 ???

Thanks guys,
P

#2

Please note, I already know about the O2 sensor :slight_smile:

#3

I will be honest. Saying coil packs fixed that makes no sense. There isn’t anything that of right now that would make that make sense or tie them together.

Here is how it breaks down

When you can’t go over 40 mph that’s a throttle body error. One of the throttle bodys came out of sync. Of you would have stopped the car turned off the car turned the key forward but not started the car for about 2 min it would have cleared the fault and ran the throttle body adaption.

The EPC is electric power train control. That light came on telling you that there is some power train communication issue. In this case it’s the throttle body.

#4

That is exactly what I have told a few guys in the local club here! Then they replace their coilpacks and the trouble goes away!

Doesn’t make sense to me.

I have sold more than a few throttle bodies because the gears inside will wear away. I will open mine up and have a look.

Will report back my findings!

-P

#5

Let us know what you find. I would be willing to bet that simply disconnecting the battery to do the coil packs was all it took for the car to clear the throttle body code and force an adaption.

#6

I had a different problem which ended up being a bad throttle body on my previous '05 A6. My car was surging at constant speeds on flat road or slight decline. The Audi dealer thought it was carbon build up. Online most people thought it was a bad torque converter and others pointed to bad fuel delivery issues. I spent way more than I want to admit trying to track it down. The throttle body was cleaned and adapted several times in the process. However, it wasn’t until the local VW dealer service dept looked at my car and predicted that it was probably a bad/cracked throttle body. I bought a used one for $70 and that solved the problem once and for all. Unfortunately, it took 18 months and thousands of dollars to figure out. My point is that the scans never showed a problem with the TB, nor did any visual inspections show a problem with the TB but that was in fact the problem.

#7

Hi all,

I left the car as it was to see if I could the get the problem to re-occur, and last night was very successful, UGH

I managed to get the car going again after waiting another 10 minutes, and drove for another 30 minutes or so, but the traction control light came back on, and the EPC light would flicker at idle RPM (moving and not moving - stuck in traffic). At idle was misfiring.

I drove about 20km, and then it cut out again - limp mode. This time I could not get the car to reset itself. Left it for over an hour, and still no go. So it was safe to say whatever was failing had gone for good.

Got it home in limp mode, and took it apart. Checked the throttle bodies - opened the up, check the gears, and moved the valve manually to ensure movement was OK. Both look just fine!

Then, replaced all the coilpacks and spark plugs. After this, the car’s running perfect!

So, still can’t be 100% sure, but all indications say the coilpacks have had an effect. I’ll be sure to post here again if the issue re-occurs, but if this is the last update, then this should be your first step should you get a similar issue.

-P

#8

Did you get a chance to pull the codes again.

I think a great way to put this to rest is to keep your old plugs and packs. See if the issue comes back on your current plugs and packs. If it does then we know those didn’t fix it. If you don’t see anything for a few months try putting the old plug and packs in and see if it comes back. When you do put the old plugs and packs in just make sure to keep a vagcom on you.