A method for diagnosing an electromagnetic actuator of a sliding cam valve drive of an internal combustion engine. An actuator pin is released by electrical energizing of the actuator and is introduced into a groove-like sliding slot which passes through a cylindrical slot section of the associated sliding cam-and ends in a slope onto the cylindrical circumference of the slot section. The method includes: energizing the actuator using current parameters of a variable actuator characteristic map so that the actuator pin is released when the cylindrical circumference overlaps the actuator pin circumferentially; determining whether the released actuator pin generates a rejection signal due to the slope from the sliding slot onto the cylindrical circumference; if no rejection signal is detected, repeating step a) whereas at least one current parameter is changed and step b); updating the actuator characteristic map with the changed current parameter.