Patent ID: 8127596

Claim:
A method for verifying the tightness of a tank venting system of a motor vehicle, wherein the tank venting system comprises: a tank venting valve in a regeneration line, which connects a storage container collecting fuel vapor from a fuel tank to an intake pipe of an internal combustion engine, a stop valve for sealing the tank venting system so that it is air-tight against an atmosphere prevailing outside the vehicle and a bistable pressure switch, the switching states of which indicate that the pressure in the tank venting system is above or below a predetermined switching pressure, the method comprising the steps: waiting for the vehicle speed to drop below a threshold, opening the tank venting valve, controlling the stop valve such that the pressure in the tank venting system alternates from above the switching pressure to below the switching pressure, thereby toggling the bistable pressure switch, closing the tank venting valve when a negative pressure has been attained that is below the switching pressure, measuring the period from an initial pressure that is below the switching pressure until the next time the pressure exceeds the switching pressure, assessing the tightness using the measured duration.