no change occurs synchronously with the fuel tank ventilation valve being activated to open and close as is depicted using a second time t 2 a fuel tank ventilation valve 7 which is not intact i e defective sticking open or closed must be assumed a check of the operational capability of the fuel tank ventilation valve 7 can even then be conducted with the method which basically examines a correlation between the abrupt activation of the fuel tank ventilation valve 7 to open or close and the intake manifold pressure p s which occurs in the process and allows for a conclusion to be drawn herefrom whether the fuel tank ventilation valve is intact if when opening the fuel tank ventilation valve 7 no hydrocarbons are flushed out of the activated charcoal filter 5 which lead to a significant change in the mixture such a change in the mixture is used in the technical field for checking the operational capability of the fuel tank ventilation valve 7 this check fails if a loading of the activated charcoal filter is not present and also to the extent that a change in the mixture does not occur when said fuel tank ventilation valve 7 is properly opened as a result of the previously described method a check of the operational capability of the fuel tank ventilation valve 7 is on the other hand also possible when u201c flushing u201d an unloaded activated charcoal filter 5 by detecting a correlation between the activation of the fuel tank ventilation valve 7 to open or close and the intake manifold pressure the method described above can for example be implemented as a computer program on a computer in particular in a control unit 8 of the internal combustion engine 1 and be run thereupon.