The sensor is installed on the left in the gearbox housing near the drive shaft flange.
Remove the instrument panel.
Remove the blue 26-pin connector and connect the VAG 1594/16 measuring adapter to it.
Caution: Only use the specified adapter for testing, otherwise the sensitive contacts of the plug may be damaged.
Connect an ohmmeter between contacts 20 and 21.
Raise the vehicle from the front left side so that the front wheel can rotate freely.
Turn the front left wheel by hand.
The readings of the measuring device should fluctuate between 0 and Ohm. Otherwise, find a wire break or replace the speedometer sensor.
Automatic transmission
Connect the voltmeter to contact 16 (+) and (-).
Turn on the ignition and move the car 1 m forward or backward. The voltage should increase from 0 to 12 V, and then drop back to 0 V. If necessary, find and fix the wire break according to the diagram or replace the sensor.