Beginning with MY2013, the filler necks of all A3 TDI vehicles are equipped with a misfueling guard (Figure 1). The guard minimizes the likelihood that fuel other than ultra-low sulfur diesel will be put into the vehicle.
The misfueling guard is designed to remain in a locked position when a nozzle with a diameter typically suited for non-diesel fuels (approximately 13/16?, or 20.6mm) is inserted, to prevent further insertion of the nozzle into the filler neck.
A nozzle with a larger diameter typically suited for diesel fuel (approximately 15/16?, or 23.8mm) will unlock the misfueling guard when inserted, allowing the nozzle to be further inserted into the filler neck.
