fimli

Hi guys,
I recently purchased a 2013 Audi A6 3.0 TFSI. I recently had some issues with it. When the car has not been started for some time, it takes a few seconds longer for the car to start. My mechanic (who is also my friend) advised me to change the fuel pump. Everything was fine after that. Yesterday when I tried to start the car, the was no crank at all. I had to try a couple of times before the car started. Once the car was on, there were a lot of errors (EPC, stability, engine checklight, tyre management,etc). The car was also in limp mode. I drove the car slowly to my friends workshop. Today, he tried changing the relays located at the engine bay (ECM relay and starter relay). However the problem still persist. My mechanic thinks that the started might be a problem, however if it is, why are there errors appearing? BTW I just changed the battery, so that shouldn't be an issue.

fimli

I couldn't edit the previous post, so here are pictures of the error messages in correct orientation

payedmercenary

What brand and type of battery did you install? On a problem like this I would usually lean towards a low voltage problem.

fimli

it's bosch battery, din 100. i just changed it 2 weeks back. If the battery was weak, wouldn't it be shown as an error when I scan?
I will be changing the starter tomorrow. Will keep you guys updated.

DanfZX14

You may want to have an electrical/charging system test done before you start swapping out parts IMHO.

fimli

Update:
I have replaced the starter, and the problem is still there (difficult to start, when it does start, there are a lot of errors! At one point the engine also misfires). I took the car to another workshop and according to them, its the ECU/DME.

Question:
Is it possible to replace the ECU with a used unit?? Do I have to reprogram the ECU or is it plug and play? I found a used unit taken out of an A7 (the part number is same as mine).

fimli

I am sorry if its obvious but how do u go about doing that??

DanfZX14

Any decent repair shop has the ability to test the electrical components in the starting/charging system to make the the alternator, starter, battery, etc are up to snuff before you just start swapping out parts in hopes of getting it right

fimli

I took the car back from the workshop today as they were asking me to change the ECU/DME and were quotating me a high price. I know another guy who can repair the ECU and I was planning to send it in tomorrow. When I took the car out of the workshop, everything was fine. In fact the car could start normally and there were no errors. Drove the car back to my place.

I wanted to fill up petrol and when I tried to start the car, the same thing happened (difficult to start, lots of errors). But things got worse! The car was stalling, gear changes were not smooth and there were weird sounds coming from the engine. Now I can't even drive the car! When it starts, the engine dies almost immediately. What really worries me is the sound from the engine. I really hope I didn't damage anything.

fimli

i forgot to mention, there were 2 error messages when the car was scanned using VCDS:-

1)U0401 (Implausible Data Received From Engine Control Module)

2)P3088 (Starter Relay)

He could erase the 2nd error, but not the 1st one