51 21 003 Replacing Door Detent (Lock Striker), Front Left or Right

Release screws (1) and remove door detent (3).

Installation: 

Basic adjustment via crosswire on B-pillar (4) and notches (2) on door detent (3).

Tightening torque 51 21 3AZ  . See 51 21 FRONT DOOR LOCKS

Adjust door detent.  See 41 51 004 ADJUSTING LEFT OR RIGHT FRONT DOOR

Fig 1: Identifying Door Detent

Courtesy of BMW OF NORTH AMERICA, INC.