Water In Fuel Sensor: Description and Operation

GF47.20-P-2105TU Component Description For Fuel Filter Water Level Sensor
- with CODE (494) USA version







Location
The water level sensor is inserted from above in the fuel filter.

Task
The water level sensor detects the water level in the fuel filter.







Function
The water level sensor determines the electrical resistance between electrode 1 and electrode 2.

If the fuel lies between the electrodes, the water level sensor does not send an output signal. If the water level in the fuel filter rises up to the electrodes, the electrical resistance between the electrodes drops. The drop in electrical resistance is detected by the integral electronics and sent to the CDI control unit (N3/9) in the form of a voltage signal.

If the water level in the fuel filter is too high, the CDI control unit sends a message to the instrument cluster (A1) via the Control Area Network Bus Class C (engine compartment) (CAN-C).

In order to avoid electrolysis (corrosion of the electrodes), the measurement of an ac voltage is used.