Located in side of fuel filter, at bottom of canister on 2002-2003 models.
Located on top of fuel filter moisture sensor for 2004-2006 models. (2007-2009 V6 diesels use a different coupling on top, see below)
Located on fuel hose and fuel filter for 2007 and later models
Used for bleeding any water and /or air from fuel filter and fuel system.
Sprinter II 2007-2018
O-ring is furnished with this bleed screw.