Fellow Brickboarders - On our 1989 740 brick, about a week ago, the check engine light flashed on when the car was first started and then went out promptly. More recently, the light is coming on briefly every time the engine is started, then goes out. Per the FAQ, we checked for codes using both the 2 and 6 sockets but each time got the 1-1-1 clear reponses. Our mechanic is suggesting that we replace the O2 sensor. Have reviewed previous posts with similar problems but answers seem elusive. Would a vacuum leak on the a/c control system cause this? Any help most dearly appreciated, as always!