Originally Posted by JStang
I've got 99 problems but my N54 ain't one.
first thing that came to to my mind
i had problem with a wastegate not closing properly that led to my turbines being replaced.
then i had the same symptoms (underboost codes) but it a broken nipple on one of the vacuum solenoids. (the part that the vacuum hose plugs into) new solenoid and done.
other than that, my car has been pretty good, maybe some rough cold idles, but that's it.