2002 Audi A6 3.0L V6 GAS; Wagon;. 2003-2004 Audi A6 3.0L V6 GAS; OE Has Tether;. 2005-2006 Audi A6 3.0L V6 GAS;. OE Equivalent Fuel Tank Cap;. Fuel Tank Cap;. Gates - Driven By Possibility. Two-way action pressure relief/vacuum relief valve allows fuel tank to ?.