Just wanted to bump this thread with some newly discovered information I got after getting this "overboost" code (along with 3100) and determining that there was no issue with solenoid, wastegate, vacuum lines, pressure converter, or anything else that would be logically related to this code. This was after diagnosis and repairs by both trusted independent shop and dealership AND after some unnecessary turbo-related repairs. My E92 has never had any tuning mods.
Long story short, there was never any issue with turbo boost or anything similar. There was an intermittent misfire on cylinder 5 under heavy load between 3K and 4K RPM. Dealer traced it to either (1) dirty intakes or (2) clogged/malfunctioning injector. I am on my second set of injectors, and didn't want to shell out the price of a new set for a 9 year old car. So I had them do the walnut shell blast and I put a bottle of Chevron Techron through the tank. I can't say the problem is solved 100%, but it's very close to that. Very little misfiring, no codes, and no limp mode!
But the incorrect diagnosis and misleading code from the OBD cost me extra money.
