2710700 Removing and installing/replacing control unit for transfer box (ATC 300): Replacement
WARNING: This page is about a different car, the 2011 BMW 328xi, 2010 BMW 335xi, 2010 BMW 328xi, 2009 BMW 335xi, and 2009 BMW 328xi. However, it is still accessible from the selected car via links, so may be relevant.
Before and after replacement, execute the "Repair" service function with the BMW diagnosis system.