Step one is to remove the rear bumper. There's 6 screws along the bottom edge, 2 in the wheel wells almost in the very corners of the bumper, and 3 underneath the air spoiler (I left these out when swapping bumpers during testing). You don't need to jack up the car. With all the screws out, grab one side and pull sideways from the wheel liner. The wiring is connected by one plug.
Porsche came up with a strange mounting system for the parking sensors. Here's how the sensor fits, and all the elements:
Part numbers (from left to right):
- housing 996.505.865.00
- sensor 996.606.171.00.9A4
- ring (Really, a rubber washer. More on this later.) 996.606.471.00
- retainer spring inner 996.505.667.00
- retainer spring outer 996.505.669.00
- washer 999.025.262.02
- cover inner left 986.505.859.00
- cover inner right 986.505.860.00
- cover outer left 986.505.861.00
- cover outer right 986.505.862.00
These are for cars until MY02, parts for MY03 and later are different. The inner/outer is position relative to center of bumper. Notice the only parts that are unique to a Boxster are the covers as the 996 bumper has a slightly curvier shape.
Also worth mentioning is that the outside left cover is (usually) painted white on the inside as this sensor is special. You see, this is a complex system that communicates between the sensors and one of them is the "primary".
The sensors themselves are Bosch sensors typical for those production years. Mine was marked as "0 263 003 010" although others might work with our control unit.