Test point 4: Remedy:
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Erase fault memory, move shift lever out of reverse gear and switch off ignition. Next, switch ignition back on, move shift lever into reverse and read out fault memory.
If the fault reappears, check the plug on the sensor for open circuit.
If no open circuit can be detected, check sensor plug, pin 1 to pin 4 and pin 1 to pin 2, for continuity using an ohmmeter. There should be no continuity.
If no short circuit can be detected, replace sensor.