VOLKSWAGEN issued a recall on the A6 model

On certain Audi A6 Quattro, sulphur in the fuel interacting with certain additives found in widely available fuel can become deposited on certain contact points on three sending units mounted inside the fuel tank. Low electrical resistance at contact points of any unit signals that the tank is full. The accumulation of sulphur deposits on contacts would increase the resistance and erroneously signal that the tank is filled with fuel while in fact it may not be full or could be empty. If a driver is not cognizant of the miles driven and the potential driving range of their vehicle from a fuel fill, the erroneous fuel level signal could cause the vehicle to become inoperable without prior warning. Correction: Fuel sending units will be replaced with redesigned sending units.