Test point 6: Remedy:

Examine battery and alternator voltage.

Select Control module supply voltage  and Sensor supply voltage  in the Actual values  menu item, and check the values with the vehicle in reverse gear and the ignition switched on.

Displayed control module supply voltage approx. 12 V

Displayed sensor supply voltage approx. 8 V

Pull off connector of number plate light and check the connector, pin 4 to pin 3, pin and sleeve side, for continuity.