Patent ID: 6959587

Claim:
A method for checking the tightness of a vessel or a tank-venting system of a motor vehicle, the method comprising the steps of: charging the vessel with an overpressure or underpressure generated by an electrically operated pressure source and determining an electric characteristic quantity of the pressure source (diagnostic measurement); heating said pressure source at least intermittently; charging a reference leak, which is operated selectively by a switchover valve, with a corresponding overpressure or underpressure generated by said pressure source and determining an electric reference characteristic quantity of said pressure source (reference measurement); comparing the determined electric characteristic quantity and the determined reference characteristic quantity; drawing a conclusion as to the presence of a non-tightness of the vessel from the results of the comparison; and wherein the at least intermittent heating takes place during vehicle operation, but, in time, outside of a diagnostic measurement or reference measurement which may take place.