A procedure for checking the functionality of an electric heating device (10) with at least one PTC-element (13, 14) is suggested. The electric heating device (10) is operated at a battery voltage. When controlling the heating device (10) it is impinged with a current and at least one measuring value is detected, which represents the current that flows through the heating device. The measuring value for the current is compared to at least one reference value with a default tolerance width while considering the battery voltage. In the case of a measuring value that deviates from the reference value an error can be assumed.