Possible causes, elimination, notes: Elimination:

Examine battery and generator voltages.

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

Control module supply voltage display approx. 12 V

Sensor supply voltage display approx. 8 V

Pull out number plate light and check for continuity with an ohmmeter on the pin and sleeve side of the plug connection pin 4 towards pin 3.