After a routine service, my mechanic and I noticed that the check engine light was on. Even after reseting the computer, the same fault showed up, " 40 air compressor". We took a quick test drive and found no symptoms of any kind, so I drove home puzzled. The next day I noticed that the idle was slightly different(eratic) and as I drove there was a slight hesitation on the throttle and periodically the idle would drop, almost dying. Back to the shop where the fault reading now included "air flow sensor". After hours of eliminating all mechanical possibilities, my mechanic feels I need a new computer. Previously my M was perfect. Fanatically maintained with absolutely no hint of any problems. Is a new computer needed? My mechanic says he has changed too many to count and is absolutely sure. Any advices would be greatly appreciated.
Thanks.