Diesel Water Watch Sensor suits both WW20072 & WW40072 models 
 
The electronic circuit board located in the base of the sensor is extremely accurate in the detction of water in diesel fuel and will activate both the electonic buzzer and LED light located inside the cabin of your vehicle allerting the driver that there is water in the diesel.
 
Overtightening the sensor in the Diesel Water Watch may cause the circuit board to distort, resulting in your alarms activating and remaining activated, even when there is no water in the fuel.