A method and device for detecting the blocking of a bleed valve (4) of a gasoline vapor filter (3) for a vehicle internal combustion engine (1), the method includes a step of controlling the maintenance of the internal combustion engine at a constant non-idle speed during a start or pre-stop phase, and at least one sequence of the following steps when maintaining the constant speed of the internal combustion engine: a step of changing the state of the bleed valve (4), a step of measuring at least one operating parameter of the internal combustion engine associated with the mixture fed into the engine, a step of comparing the values of the parameter measured before and after the change of state of the bleed valve and of determining if the variation of the parameter is greater than a pre-determined threshold.