51 21 140 Removing and installing/replacing complete lock cylinder in left or right front door

Necessary preliminary tasks: 

• Remove OUTSIDE HANDLE ON FRONT DOOR 

Release screws (1).

Remove gearing cover (2).

Fig 1: Identifying Gearing Cover With Screws

Courtesy of BMW OF NORTH AMERICA, INC.

Detach retaining clip (1).

Remove lock cylinder (2).

Fig 2: Removing Lock Cylinder

Courtesy of BMW OF NORTH AMERICA, INC.