I just got back from the audi dealer, I had them run a diagnostic on my 2004 a6 Quattro with 2.7t. They said it had a bad coolant temp sensor which I told them I just changed, then they said there was 2 of them on easy to change and one hard to get to. I cannot find reference to a second one anywhere so far. The one I replaced was back left of engine under the intake pipe. If anyone could help me figure out what they are talking about it would appreciate it.