In an EC motor, comprising a motor electronics, a signal input or a signal output, and an optocoupler for the galvanically isolated transmission of a useful signal between the motor control unit and the signal input or the signal output, the intention is to reliably determine the degradation of the optocoupler and to improve the service life of the EC motor. This is achieved in that an evaluation unit regularly evaluates a saturation voltage of the optocoupler at the output of the optocoupler in relation to a reference threshold when the optocoupler is wired and generates a warning signal when the saturation voltage exceeds the reference threshold.