Patent ID: 6889667

Claim:
A method for checking the operability of a tank-venting system for a motor vehicle having an internal combustion engine, the tank-venting system including: a fuel tank; an adsorption filter; a filter line connecting said adsorption filter to said fuel tank; said adsorption filter having a venting line; a switchover/check means for closing off said venting line; a tank-venting valve; and, a valve line connecting said tank-venting valve to said adsorption filter; the method comprising the steps of: introducing an overpressure relative to atmospheric pressure into said tank-venting system utilizing a drivable pressure source; detecting at least one operating characteristic variable of said pressure source while introducing said overpressure to determine the pressure course; drawing a conclusion as to the presence of a leak from said pressure course whereby a tightness check is made; and, reducing said overpressure by opening said tank-venting valve and simultaneously closing said switchover/check means.