Patent ID: 8161948

Claim:
A method for testing the function of a pressure switch of a tank ventilation system for an internal combustion engine of a motor vehicle, the pressure switch being in a low-pressure position if the pressure in the tank ventilation system is lower than a predefined pressure limit, and the pressure switch being in a high-pressure position if that is not the case, wherein the method comprises the following steps: detecting a switched state of the pressure switch, carrying out a measure that increases the pressure in the tank ventilation system above the pressure limit if the pressure switch is in the low-pressure position, the measure including: actuating a tank ventilation valve arranged in a connecting line between a fuel vapor accumulator and an intake pipe of the internal combustion engine when the internal combustion engine is in operation such that the tank ventilation system and the intake pipe are pneumatically separated; and determining whether conditions indicate a sufficient rise of pressure in the tank ventilation system for testing the function of the pressure switch, including at least one of: determining whether a detected acceleration of the motor vehicle exceeds a predefined acceleration limit; and determining whether a detected temperature of the motor vehicle exceeds a predefined temperature limit; and identifying a defect of the pressure switch if the pressure switch remains in the low-pressure position after the measure has been carried out.