I am having some serious issues with my '02 S4 2.7L. The CEL comes on intermittently when I go in the mountains or up hills, etc. I took it into the Audi dealer (under extended warranty) and had it diagnosed. The service guy told me that the CEL was coming up with "Turbo valve failure" and something about "Fuel trimming." He told me I needed to replace both valves, which I did, and went on my way. Not 100 miles later and it came on again! Then went off, and is now back on (not blinking). I also have been smelling an acrid, almost burnt rubber kind of smell...

Any help would be great!

 

Since the first dealer either mis-diagnosed or missed something altogether I would go to another dealer for the additional repairs.