30CF After Engine Replacement


New Member
Jan 23, 2019
2009 335i M-Sport
Can't figure this one out whatsoever, driving me nuts. About to take it to the dealer because I'm running out of ideas. Long story short, replaced engine with used motor. Replaced turbos with low mileage used ones, set the wastegates with a Mityvac during the install just to make sure they wouldn't rattle etc

Upon working out all of the initial kinks from the engine swap I got the car turned on, had to reset the throttle adaptations because the car was idling like shit and throwing a throttle angle code etc. Also reset VANOS adaptations for 2 VANOS codes at the time. All those codes went away but the two codes that have persisted are 30CF: DME: Wastegate, activation. and 3100 -DME: Boost-pressure control, deactivation. 3100 doesn't mean anything besides telling me its in limp mode.

I just went back to the MHD code history to see if there was any more info in there and it looks like the same two codes have always been there since the very first moment of starting the car. First code pull was the throttle adaptation values, 30CF, 3100 and then 6 injector codes because I was priming the oil pump and had the injectors unplugged. Then just 3100 and 30CF. Next code pull had VANOS codes + 3100 + 30CF + 30D0 (wastegate 2, activation. I didn't realize I threw this code as well, lately it's just 30CF)+ 2A9A + 2C7F (DME: Lambda control). Cleared the codes, pulled 30CF & 3100. Cleared codes, pulled 3100. 5 minutes later, pulled 2C7F and 3100 by itself. 20 minutes later, 2C6A (DME: Oxygen sensors after catalytic converter: mixed up) + 2C7F + 3100. Cleared codes and I have been pulling 3100 and 30CF ever since.

I have posted on a few different forums now, but never dove into the historical codes. Anything in here that would cause no boost whatsoever?!? I figure some of these codes might make the car run a little iffy but nothing should completely eliminate my boost.