Sounds live the Vanos solenoid valve is ether clogged up with crud or shot.
Potential problem source(s):
- Contaminated oil passage
at VANOS solenoid valve
- Oil pressure too low
- Defect in wiring harness to
VANOS solenoid valve
Or
Vanos Solenoid Seized.
I'd bet on the latter. This is an extremely common problem with these engines. Not too bad a repair.
FYI, this thread has a link to the codes from the N55 engine:
BMW N55 Diagnostic Code List
Look on Page 13 for your code.