I have an 02 A4 1.8T. A few months ago the local VW store (closest Audi dealer is 4 hours away) told me that the code they got was for a bad cat. I replaced the cat with an after market from Techtonics. Check Engine light came back on right away. This time I took it to te Audi dealer in Portland.

Here are the codes they gave me:

17544 P1136 001
Bank1, mixture adaption (add)
system too lean

16684 P0300 008
Rando/Multiple cylinder
Misfire Detected
Sporadic

16688 P0304 008
Cylinder 4
Misfire Detected
sporadic

16686 P0302 008
Cylinder 2
Misfier detected
sporadic

17658 P1250 008
Fuel level
too low

Car is stock except for the new cat.

Car has 74,ooo miles

Where should I start??

Thanks...

in Measuring Block 032 fields 1 and 2.

Look for any source of unmetered air entering the intake past the MAF.

I would ignore the misfire codes unless they persist after you've got the fuel trim issue squared away.

-Uwe-