A tank filler neck including a filling line having an insertion end further away from the tank, designed to temporarily insert a breather pipe into the end region of the filling line further away from the tank, a passage line end closer to the tank, designed for passing through liquid in the direction away from the insertion end, a ventilation volume designed for through-flowing gas while passing liquid through the end of the passage line, a ventilation line which ends at a distance from the filling line and which can be blocked or released by a ventilation valve for through-flowing gas, a detecting device designed to detect a passage-ready state and/or a passage state of the filling line, and an operating device 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.