check engine light on, car seems to be running ok
check engine light on on 1998 BMW 528i
I would recommend you find a high quality BMW technician close to you for assistance. Diagnostic trouble codes (DTCs) are stored in the processor. Getting these pulled will help give a trail on what tests need to be performed.
1 more answer
try diconecting you pos post on battery leave it off for about 15 min then reconnect it that should reset you computer