I happened to be at the stealership getting some parts (I know...but bavauto had to special order and it was gonna take like 2 1/2 weeks)...i noticed on the parts counter a mag. called "Techdrive" Premiere issue for indep. BMW service professionals....and FREE (yes the ONLY thing you will get from a stealership for free besides an ass pounding)
Contained great articles, one in particular about diagnosing and fixing all problems associated with the MIL (check engine light).
Too much info to write here, just figured I would let you guys know in case you happen to be at the stealer for something...pick it up....