Engine
If the bolts loosen or break the engine may have reduced power or stall. An engine stall increases the risk of a crash.
The bolts that secure the housing for the variable camshaft timing adjustment unit can loosen over time and possibly break, causing engine damage and engine stalling. Dealers will replace the four bolts for both intake and exhaust timing units free of charge to resolve the concern.
BMW notified owners of affected vehicles starting in April 2014. You can check with your dealer to see if your vehicle is involved in this program. It is helpful to have your VIN (Vehicle Identification Number) on hand when you contact them.