Water in fuel sensor for the -01 style fuel filter used on Mercedes and Sprinter models equipped with the OM642 engine.  This sensor is held into the fuel filter with two screws and must be removed and transferred to the new fuel filter during a filter replacement.  If your fuel filter is losing prime or you see excessive air bubbles in the fuel line, a broken/cracked WIF or worn WIF o-rings are a common cause.

Only for the -01 style filter, will not fit the -03 style or the 5-Pin style

Also fits Jeep Grand Cherokee CRD.