The gearbox sensor measures the rotational speed of the output shaft. It then transmits the relevant data to the computer, which selects a gear to match the speed. The sensor is located on the side of the gearbox.
A faulty gearbox sensor should always be replaced with a new one
A faulty sensor may result in increased fuel consumption and accelerate the wear of particular gearbox components
Range of services
Disconnecting the sensor from the electrical system
Removing the bolt holding the sensor to the gearbox