How's it going. I have been reading a lot of threads on this forum, as well as other Audi related forums, and while they have been very helpful, my problem still persists. I ordered an ecu from eBay, from a seemingly reputable seller. I decided to replace it because many of the sensors in my car have been replaced, as well as other major parts including the engine, and I think the turbocharger as well, but I still got error codes related to some of those sensors, and I figured swapping the ecu was worth a shot. When I put in the new ecu, I got a p0600 code, and I read I had to recode it. I had trouble getting the ecu to respond in vcds lite, but when it did, I recoded the ecu and my car started. I then shut it off, and tried to turn it on but it acted as if it wasn't recoded, and the p0600 code came back. It seems like it only responds 1% of the time in vcds, but I have been able to connect, and the new code did indeed stick. I also had the same problems trying to connect to the old ecu.

Any help would be greatly appreciated, and sorry about the super long post.

 

Progress! I have found that when I disconnect the negative terminal from the battery for about a minute and then reconnect it, the ecu will respond. However, it appears that I have to repeat this process every time, since if I turn the power on a second time before disconnecting and reconnecting the battery, the ecu does not respond. I'm starting to think my ecu relay is bad, so im going to replace it and see if that fixes the problem. The only thing that puzzles me is that my car started and ran fine before I replaced the ecu, but I'm pretty sure the ecu I put in isn't bad.

 

Replaced relay 30, didn't fix anything.