My car was idling for about 10 minutes last night in 35 degree weather, when I got in to start driving it the check engine light came on. Any suggestions of what to check on my own before I have to bring it in for diagnostics? I just had a new air filter put in about 1,000 miles ago and the mechanic said everything looked fine.

Much appreciated!

 

You might have a terrible case of carbon build-up and the only way to verify this is to have your car serviced if you don't know how to pop the manifold cover off yourself.

http://www.audizine.com/forum/showth...ad-for-RS4-4.2

There are a lot of other things it could be too but this is pretty common - you ought to have noticed problems before it got to this point if the issue is carbon build-up.

There also could be water in the fuel, a bad injector or bad fuel pump, bad coil pack, bad spark plugs or bad O2 sensor(s).

Go to Auto Zone and have them pull the code for you and find out what code is set, then post an update and that can help narrow down what to look for.