A method for diagnosing an electrically controllable pop-off valve of a turbo-charging device of an internal combustion engine, which pop-off valve is situated in a pop-off pipe bypassing the compressor, includes: providing a reading regarding an air mass flow supplied by an air supply channel to the internal combustion engine; after the activation of the pop-off valve in order to switch over the pop-off valve, analyzing the time curve of the air mass flow reading in order to determine, within a specified time after the beginning of the activation of the pop-off valve, a local maximum of the air mass flow indicated by the air mass flow reading; and detecting a fault of the electrically controllable pop-off valve if the local maximum of the air mass flow is not able to be determined within the specified time.