Ltdplus9

Well, I've been waiting for the day when my A6 is out of warranty and something goes wrong. Yesterday was that day. With 60K miles on the car, I got an EPC light and engine light with very heavy engine vibration and little acceleration. Since it was a yellow light, I decided to limp it to my local Audi servicer instead of having it towed. I probably should have had it towed. After 1 day with the Audi techs, they don't know what's wrong. How can that be?? I said aren't there codes that tell you exactly whats wrong?? Just doesn't seem reasonable. I'll wait it out but I have a feeling I 'll be looking at a hefty bill. Coincidently enough, I had only driven 50 miles following the 55K servicing (yes, I was late) where the plugs are replaced. I can't but help it feel something they did caused this problem. No other issues before that except for an intermittent audible rattle sound during the first start of the day which only last a second while the engine comes up to speed. Will let you know what they find in case someone else ever has the same problem.

DanfZX14

Sorry to hear that but be patient they should be able to figure it out and hopefully nothing serious, ie: expensive... Please do let us know when you find out what's actually wrong.

fastlane1000

The noise you are hearing at cold start is the timing chain. The link below explains and provides the TSB. Shouldn't be causing a CEL. I have the noise too.

https://www.audiworld.com/forums/a7-...-tfsi-2900612/

FastLane '12 A6 Quattro Prestige 3.0T, Uni Stage 2+, Eurocode sways and bushing inserts, 20" RS6 Reps

tenspeed

One or more of the cylinders were not firing.

That depends on how far you had to drive. A misfire sends raw fuel out the exhaust and can damage the O2 sensor.

The codes can point them in the right direction, such as pointing out if it's a random misfire (P0300) or a specific cylinder (P0301, P0302, etc.).

Since plugs were the last parts replaced, the ignition side would be the first place I would be looking. If there was a specific cylinder code, I would be swapping the coil with another cylinder to see if the misfire moves. All of my knowledge is based on standard four cycle gasoline engine. If the problem isn't something basic, it would be time to have a repair shop take a look at it.

The Audi 3.0L has some new technology that should also be added to the search of finding the root cause of the problem. The technicians have a procedure to follow. They tend to not share what they have done so far because the explanation would not be understood unless the owner knows the interconnectivity of the control systems.

Ltdplus9

Thanks Tenspeed. Thats exactly what I'm thinking and now after 2 full days with the Audi techs, they "claim" they still don't know what the issue is. I've asked them both days if they can confirm if all cylinders are firing or not, and they won't answer. They beat around the bush. Isn't that a simple question to answer after 2 days of diagnosing the problem? Shouldn't they be able to tell me if all cylinders are firing or not?

Bartenderfloyd

When this happened to my 2004 A6 it was the coil packs. Same symptoms.

tenspeed

Most likely that the techs have been directed to keep their mouths shut until the problem has been discovered and the repair approved. Could have been a situation where they did talk to someone and then the problem found was much more expensive than what they thought.

IknowHuhA6

I agree with TenSpeed and think he's right on the nose. Get the full write-up of what they think is wrong then let us know. Chances are you can take the car to a different shop at half the cost. If the diagnosed problem is easy enough for a DIY, there may be a thread to help you take care of it at minimal cost. We just need the details of what they claimed to have found.

Personally, I like and prefer the option of having dealer diagnose my car. I then either fix it myself or pay trusted indy shop at half the cost.

Oh and if you wouldn't mind, could you please post the codes that came up when you get these?

Thank you.

Ltdplus9

Did Audi fix or someone else? How much $$??

Ltdplus9

I sure will. Thanks