The invention relates to a modular unit (10) comprising a sensor device (11) for actuating a movable part (1, 33), in particular a flap (1) of a motor vehicle. Said unit comprises a support element (12), on which the sensor device (11) comprising at least one sensor (21, 22, 23) is situated, in order to detect (3) an object (4) in a detection region (5, 6, 40) that borders the motor vehicle (2), the detection operation (3) initiating the actuation of the movable part (1, 33). According to the invention, the modular unit (10) is designed as an individual module (10) that is easily fitted in such a way that said unit (10) can be fixed to the motor vehicle (2).