The invention relates to a method for checking the function of at least one PTC heating element which is used in a device for providing a liquid additive. The at least one PTC heating element is connected to a voltage source via electric conductors. According to the method, a starting current with a first value is provided at a specified operating voltage in a step a). Then, in a step b), a monitoring process is carried out in order to determine whether the starting current with the first value is provided for a minimum duration, said minimum duration having a value of at least seconds. The method is used in particular for on-board diagnoses of a device for providing a liquid additive.