In order to regenerate an activated carbon filter which is seated in a tank vent line, during idling of the internal combustion engine the regeneration valve is brought into the maximum open position, and the throttle valve is simultaneously opened slightly. This produces a higher air mass flow in the intake tract of an internal combustion engine, and the proportion of hydrocarbons introduced by the regeneration remains constant. In order to keep the idling speed of the internal combustion engine constant, a torque reserve is built up, for example by adjusting the ignition angle.