51 21... Removing and installing left or right lock barrel of front door

Necessary preliminary tasks 

• Remove CARRIER FOR OUTER DOOR HANDLE .

Release screws (1).

Remove gearing cover (2).

Fig 1: Identifying Gearing Cover And Screws

Courtesy of BMW OF NORTH AMERICA, INC.

Press down latch mechanism (1) slightly.

Turn lock cylinder (2) in direction of latch mechanism (1) and remove.

Fig 2: Identifying Lock Cylinder And Latch Mechanism

Courtesy of BMW OF NORTH AMERICA, INC.