This water-in-fuel sensor detects the presence of water in the fuel system and sends a signal to the machine's electronic control unit. It is installed in the fuel filter housing or water separator assembly, where it monitors the water level that settles at the bottom of the bowl. When the water level reaches a predetermined threshold, the sensor triggers a warning light or message in the cab, alerting the operator to drain the separator. A failed sensor may not detect water accumulation, allowing moisture to reach the injection system and cause corrosion or injector damage. This original component matches the housing's sealing interface and electrical connector configuration, so no adapter or wiring modification is required during replacement.