An electronically commutated electric motor includes a stator and a rotor formed as a permanent magnet. A control unit is connected to the stator and configured to energize the stator to produce a rotating magnetic field. The electric motor further includes at least one Hall sensor configured to detect at least a magnitude of a sensor magnetic field produced by a sensor magnet connected to the rotor. The electric motor also includes at least one magneto resistive sensor configured to detect an alignment of a total magnetic field during a rotor revolution of the rotor and to generate a rotor position signal representing this alignment. The total magnetic field includes the sensor magnetic field and an interference magnetic field superimposed thereon. The control unit is further configured to determine the rotor position of the rotor at least depending on the alignment of the total magnetic field.