EXPANSION TANK CAP; A6 Allroad. EXPANSION TANK CAP; A6 Quattro. A cover that prevents foreign debris from entering the container. From 06/15/2020. From 06/22/2020. From 11/21/2016. Location-Reservoir. Radiator Cap. To 06/15/2020. To 06/22/2020. To 11/21/2016. Included with: Reservoir, Reservoir tank.