A method monitors a sensor clock signal in a sensor unit, which is generated and output for a data transfer between the sensor unit and a control unit with a predefined period duration. A reference clock signal having a predefined reference period duration is received. The sensor clock signal is compared to the reference clock signal. Based on the comparison, a deviation of the current period duration of the sensor clock signal from a target period duration is detected. Based on the detected deviation, a counting pulse or a reset pulse is emitted.