The fog light full set is situated on the front and rear of the vehicle and is used when driving in poor visibility conditions such as fog or falling snow. The fog lights on the rear of the vehicle are coloured red, and those on the front of the vehicle are coloured white. This is to help other road users work out if a vehicle is driving away from them or towards them on the road.
The fog light full set differs to the other lights on the vehicle because it’s beams are low and wide to create a narrow bar of light running along the road to illuminate the road surface. In rear fog lights, these are used more for the benefit of other drivers behind you so that they are aware of your vehicle. In the front they illuminate any road obstacles ahead.
Because of the intensity of the beam, fog lights have restrictions on when they can be used. If used when visibility conditions are fine, these could temporarily blind other drivers and cause collisions.
Failure of a fog light full set is an MOT failure and should be corrected quickly.