Method for the activation of a tank venting valve of a motor vehicle during a leak test

A method of regulating a fuel tank venting valve of a motor vehicle during leak testing of a fuel tank venting system where the fuel tank venting valve is arranged in a recovery line that connects a retention vessel to catch fuel vapors from a fuel tank to an inlet manifold of an operating internal combustion engine, comprising:

• sealing the tank venting system from the atmosphere outside the motor vehicle;
• opening the fuel tank venting valve to expose the fuel tank and the tank venting system to a relative negative pressure present in the inlet manifold of the operating internal combustion engine;
• and
• regulating the degree of opening of the tank venting valve based upon a function depending at least in part on the external ambient pressure outside of the motor vehicle, pA, and a gas mass flow, {dot over (m)}soll, through the valve, wherein an offset value, Δ{dot over (m)}, for regulating the fuel tank vent valve or for the correction of the nominal gas mass flow, {dot over (m)}norm, is determined from a characteristic map which uses the external ambient pressure (pA) as an input, and
• wherein the regulation of the fuel tank venting valve improves the fuel system leak test accuracy.