Ok, I'm a mechanic and welder by trade but have no access to VAG or OBD2 for my 01 S4. A few days ago I started having trouble at 110,500 miles. While cruising up a hill i n6th at a normal speed the EPC light came on in the dash and the car went to power failure mode(like 3000 rpm or less or something)......now.....3 days later it came on again. It goers away after I turn the car off and restart and runs fine. Well tonight I had to do this 4 times in row in about 2 miles (it was raining if that means anything) and then the engine malfunction light came on. It's the light that looks like an engine with a lightning bolt in it. Well, the first tiem it happened I thought...."oh God, my turbos just went"....wellll obviously that's not the case. I am gonna have it diagnosed but just looking for opinions. My first three guesses are MAF sensor, O2 sensor or catalytic converter? Any other suggestions, experience or help? Thanks. Dave

 

Post the codes when you get them, then we can help