A method for diagnosis of a tank ventilation valve in a tank ventilation system for an internal combustion engine of a motor vehicle includes actuating a tank ventilation valve via a control unit, and checking the functionality of the tank ventilation valve in a manner dependent on a pressure oscillation measured by the pressure sensor. The tank ventilation system includes a filter having a first feed line from a fuel tank, a second feed line with a connection to a surrounding atmosphere, and a third feed line to a tank ventilation valve, wherein the tank ventilation valve has a connection to two different introduction points at an intake pipe, wherein the connection has a first line system and a second line system, wherein the tank ventilation system further includes at least one pressure sensor installed in the second line system between tank ventilation valve and intake pipe.