A3 weird squealing noise
 

Hi, all. I'd love to put your collective knowledge to test, so here goes...

We have a 2006 A3 2.0T automatic with 32k miles. The Check Engine light came on during the drive home, followed shortly by a medium-high pitched singing/squealing noise that came and went but then grew louder and more constant until getting home. It didn't change pitch or waiver during this time.

After letting it sit for a couple days, it no longer made the noise - so we drove it for in-town errands. It took about 30 miles with a couple of starts & stops - and the noise returned. So it seems to happen only once the car is good and "warmed up".

After reading other posts, I'm thinking it's not necessarily a s-belt tensioner but maybe the water pump or something with turbo? The noise definitely comes from the engine area - closer to the dashboard than the front bumper.
We're planning to take it to the dealer since it's still under warranty but I hate to get stung for a diagnostic charge if it's something easy to correct.

Greatly appreciate any thoughts & help.

Thanks.

DLMayhem

Just take it in. They should not charge you for checking since its under warranty. If they do find a different dealer to go to.

Is your oil cap on correctly? Does your dipstick a broken clip?

I say this because I have had allot of engine pressure noises over the past few months. Coming from older VWs and a Nissan, that did not have high compression engines, engine pressure was not much of a problem. Since August of last year I have had a coolant leak, blew a diverter valve, found my oil cap on upside/down, and went through numerous dipsticks (I keep breaking one of the two plastic clips)

I was getting squeal noises on upshifts and did not know why. After having the diverter valve replaced, the noise was still there, then I felt a loss of power and found out my diverter valve blew. I also found my oil cap on upside down (did I do it or the dealer?). After replacing my dipstick for like the fourth time and breaking another plastic clip two weeks later, I didn't replace the dipstick and my noises were still present. When I saw oil coating the orange dipstick top piece, I figured the engine pressure was blowing oil out because one of the clips was broken. I have since replaced the dipstick and my squealing noise has went away.

I don't know much about engines, but hope my advice will help you some, and like 4RINGSROD says, your still under warranty, take it to your leader (dealer, hahaha).

Took it to the dealer
 

We found out that not only is it still under warranty, but there's a zero maintenance plan on it as well. Nice bonus.
The squeal turned out to be an inoperative flap actuator on the intake. The mechanic said that they are cheepie plastic and they crack - he's seen a couple already. The CEL was unrelated to that issue - it was a fuel trim thingy running too lean as well as a pcv valve/hose that needed to be replaced (according to the paperwork).
All that fixed & an exterior bath too. Yay.

Now we just need to work on getting a second key for something less than the dealership wants ($250!!).

Thanks all.