Tank filler neck

A tank filler neck for a motor vehicle, the tank filler neck comprising a fill hose defining a filling line having an insertion end in a ready-assembled condition further away from an associated tank, the filling line having a passage end in the ready-assembled condition closer to the tank, which is designed for passing through liquid away from the insertion end, said fill hose comprising an upper fill hose, which includes the insertion end, and, at a location away from the insertion end, a lower fill hose attached relative to the upper fill hose with a gap formed in between the upper and the lower fill hoses, wherein the tank filler neck furthermore has a ventilation volume which is designed for through-flowing gas while passing liquid through the passage end, the tank filler neck has, for providing the ventilation volume, a ventilation line for discharging gas ending at a distance to the filling line and which can be blocked or released for through-flowing gas by a ventilation valve wherein the ventilation valve is adjustable between a blocking position and a release position and wherein the tank filler neck furthermore has a detecting device which is designed to detect a passage-ready state and/or a passage state of the filling line, and, furthermore, has an operating device which is designed to adjust, as a function of the detection result of the detecting device, the ventilation valve between the blocking position and the release position, wherein the ventilation line has a ventilation chamber surrounding the filling line on the radial outside and penetrated by the filling line, wherein the upper fill hose, over its entire length, separates the ventilation volume from the filling line with the gap opening into the ventilation volume, wherein the ventilation valve is provided to open and close off a ventilation opening through which gas can be discharged from the ventilation chamber.