My 2002 M5 recently sputters during acceleration, once even stalled at a red light, and the Engine Failsafe Prog error lit up. I brought it into the dealer. The first time, the tech claimed to do a software upgrade (related to the DME?) and the problem would be solved. Needless to say, it wasn't solved.

I took the car back, and this time they found the problem is the throttle position sensors in bank 1 and 2 failing, and will need to replace them. They're quoting me $800+ to do the job. Does this sound right? The dealer is Stevens Creek BMW in San Jose, CA.

Please advise.