Before installing the parking assist distance sensors, put the resilient O-ring spacer all the way around the sensor membrane protrusion, with its wide end touching the sensor housing and its narrow edge pointing toward the front and toward the rear car bodywork. Then, line up the sensor (4) with the sensor bracket (3) on the back of the rear bumper fascia (2), pushing it in until you can see that the sensor membrane is even with the outer part of the fascia. Be sure that each sensor membrane is correctly centered in the fascia's openings and that none of the O-ring spacers is pinched, as this can harm parking assist distance sensor function. With that done, attach the wire harness (1) to the sensor connector part that's on the back of the fascia. Afterwards, secure the bumper fascia onto the rear part of the car and join the negative battery terminal.