A key device for opening or starting a vehicle includes a main body, and at least one cleaning means which is in or on the main body for cleaning an optical element of a rear view device of the vehicle. Further, a method is provided for cleaning an outer element of a vehicle, in particular at least one optical element of a rear view device of a motor vehicle by detecting a contamination state including a predetermined degree of contamination or a predetermined type of contamination of the outer element, emitting at least one signal that is characteristic for the detected degree of contamination including an input signal for a key device, and transmitting an optically, acoustically, or haptically detectable output signal by the key device, with a request for cleaning using the at least one cleaning means of the key device or which is connectable with the key device.