A method for diagnosing a diverter valve of an internal combustion engine having a compressor is provided, for which diagnosis a variation over time of a charging pressure of the internal combustion engine as a result of a predefined triggering of the diverter valve is analyzed, the triggering of the diverter valve taking place in such a way that a diverter valve moved in the direction of its closing position is expected. Depending on the resulting variation over time of the charging pressure, an open jamming diverter valve is diagnosed if the variation over time of the charging pressure is not plausible with an expected variation over time for a diverter valve moved in the direction of its closing position.