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

Necessary preliminary tasks: 

• Remove carrier for outside door handle with lock cylinder

Lever retainer (1) out of lock (2).

Pull retainer (1) out of guide (3).

Connection between carrier (5) and lock cylinder (4) is released.

Installation: 

1. Catches (1) of retainer (2) must not be damaged.

Pull lock cylinder (1) out of carrier (2).

Installation: 

Following parts on lock cylinder (3) must not be damaged or missing:

1. Paddle
2. Guides
   Fig 4: Identifying Lock Cylinder Parts

   Courtesy of BMW OF NORTH AMERICA, INC.