A method for detecting a fault in an electrical machine, e.g., a synchronous motor, a motor control unit for controlling an electrical machine, and a motor arrangement having such a motor control unit are disclosed. According to the method, rotation angle data are determined, which data are dependent on a rotation angle of a rotor of the electrical machine in the absence of the fault. In addition, additional data are determined and allow conclusions to be drawn on the fault. A fault is detected if the rotation angle data satisfy a first criterion and the additional data satisfy a second criterion.