The invention relates to a method for detecting a functional impairment of a laser scanner (2) of a motor vehicle (1), wherein a laser beam (12) of the laser scanner (2) is emitted through a protective pane (6) of the laser scanner (2) into a surrounding region (4) of the motor vehicle (1), wherein an echo (16) of the emitted laser beam (12), which laser beam is at least partially reflected at the protective pane (6), is received by a receiving unit (9) of the laser scanner (2) having an intensity value (19), and the functional impairment of the laser scanner (2) is detected if the intensity value (19) is different from a reference intensity value.