In order to be able to reliably detect when an object is caught between two parts which move in relation to one another in a motor-driven closing mechanism, in particular in an electromotively driven window winder system, provision is made for the sensor system to have an optical pressure sensor as well as an electrical capacitive sensor in addition. The optical pressure sensor comprises a light-guiding element, a light source for injecting light into the light-guiding element and a light sensor for sensing the light which has been output. The electrical sensor comprises an electrode which is connected to a voltage source. Both sensors are each assigned to an evaluation unit for evaluating the respective signal.