Theory of Operation
WARNING: This page is about a different car, the 2011 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The Water-In-Fuel Sensor is attached to the bottom of the fuel filter. The Powertrain Control Module (PCM) provides a 5-volt reference signal to the Water-In-Fuel Sensor. When the water collected in the fuel filter covers the sensor probes, the Water-In-Fuel Sensor then pulls the 5-Volt reference voltage to ground indicating high water accumulation in the fuel filter. The PCM illuminates the MIL lamp immediately after the diagnostic runs and fails. During this time water in fuel may cause white smoke, loss of power or hard starting. The MIL lamp will turn off after the diagnostic runs and passes in four consecutive drive cycles.