Version up to 10/2003:

WARNING: This page is about a different car, the 2003 BMW X5 and 2002 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.

In bumper, center:

Lever out ultrasonic transducer (1) including holder.

In bumper, side:

Unclip side cover (2).

Fig 1: Levering Out Ultrasonic Transducer Including Holder

Courtesy of BMW OF NORTH AMERICA, INC.

Unfasten plug connection (1) and disconnect.

Unclip ultrasonic transducer (2) and pull out of holder.

Fig 2: Unclipping Ultrasonic Transducer

Courtesy of BMW OF NORTH AMERICA, INC.