Water in Fuel Indicator Sensor for Duramax 6.6L Chevrolet Silverado and GMC Sierra Engine 2001-2011 Truck.<br><br>Function:<br>Let the Engine Control Unit(ECU) and/or dashboard lamp indicator know when water detection has occurred in the vehicle's fuel supply.screws into the bottom of the fuel filter housing and has a valve in the bottom that can be used to drain water<br><br>Replaces OEM part number:<br>12639277,12639450, 97384931