Abstract: The disclosure describes a method for operating a speed sensing device including a magnetically operating speed encoder that is located on a rotatably mounted shaft and a fixed sensor configured to interact with the speed encoder. The speed encoder includes at least one encoder element configured to move past the fixed sensor upon a revolution of the shaft and thereby produces an electrical pulse. The sensing of the electrical pulses produced determines the speed of the shaft. For at least a plurality of successive electrical pulses, the respective time of a signal period for at least two successive electrical pulses is measured and stored, and the respective time of at least one selected test period for the signal periods is compared with (i) the time of the previous signal period, and (ii) with the time of the subsequent signal period in order to detect absent and/or incorrect electrical pulses.