I have a 2004 745Li and my "Service Engine Soon" light just came on. The car was just services about 3 months ago. It came on a couple of days after accidently putting regular 87 gas in the vehicle. Perhaps a coincidence? I did the gas cap thing but that didn't work. Regardless, I need advice. Should I take my car to BMW for service? Ouch! Do an Indian raindance? HELP!