Working in an Independent shop leaves something to be desired when it comes to fault code diagnosis. I have been working on a 1997 E320 with 88K miles on it. Twice about three weeks apart, it has set a code in the engine management system . The code is P0170 which is a fuel trim fault. The basic descriptions for failures don't seem to apply. Those are fuel pressure, vacuum leak, worn engine, etc. Has anyone out there ventured into this part of the OBD II world? Your thoughts would be much appreciated.
Thanks for yuor help.