§ 17 StVO
(1) During twilight, in darkness or when visibility conditions otherwise require it, the prescribed lighting equipment must be used. The lighting equipment must not be covered or dirty.
(2) It is not permitted to drive with marker lights (parking lights) alone. On roads with continuous, adequate lighting, it is also not permitted to drive with high beam. The headlights must be dimmed in good time if a vehicle is approaching or travelling at a short distance ahead or if the safety of traffic on or beside the road otherwise requires it. If necessary, slow down accordingly.
(2a) Anyone driving a motorbike must also drive with dipped headlights or daytime running lights switched on during the day. During twilight, in the dark or if visibility conditions otherwise require it, dipped headlights must be switched on.
(3) If fog, snowfall or rain significantly impairs visibility, then dipped headlights must also be used during the day. Fog lights may only be switched on in such weather conditions. If there are two fog lights, it is sufficient to use the marker lights instead of the dipped beam. On motorbikes without a sidecar, only the fog light needs to be used. Rear fog lights may only be used if visibility is less than 50 metres due to fog.
(4) Stopping vehicles outside built-up areas must be illuminated with their own light source. Within built-up areas, it is sufficient to indicate only the side of the vehicle facing the carriageway by means of parking lights or in another approved manner; own lighting is not required if the street lighting makes the vehicle clearly visible at a sufficient distance. Vehicles stopping on the carriageway, with the exception of passenger cars, with a maximum permissible mass of more than 3.5 tonnes and trailers must always be illuminated with their own light source or identified by other approved lighting equipment within built-up areas. Vehicles that can be easily removed from the carriageway, such as motorbikes, bicycles with an auxiliary motor, bicycles, patient lifts, single-axle tractors, single-axle trailers, manual vehicles or unharnessed carts, may not be left unlit in the dark.
(4a) If military vehicles deviate from the general lighting regulations, yellow-red retroreflective warning signs or equivalent safety devices must be used. Otherwise, they may also be used on these vehicles.
(5) Anyone travelling on foot and carrying single-axle towing or working machines on bars or manual vehicles must attach or carry at least one white light on the left side that is clearly visible to the front and rear and does not dazzle.
(6) Searchlights may only be used briefly and not to illuminate the carriageway.
Quelle: https://www.gesetze-im-internet.de/stvo_2013/__17.html
