A sensor device for a monitoring of a coupling state of a coupling element, in particular a coupling bolt, preferably a kingpin, of a trailer, in particular a semitrailer, with a corresponding coupling element of a towing vehicle, in particular a semitrailer tractor, with at least one sensor which is at least configured for a recognition, in particular a detection, of a relative position of the coupling elements with respect to each other,



wherein the sensor is realized as an ultra-wideband sensor.