I know there are some lovely upgrade LED options for the fog and reverse light on a Caterham, especially from Just Add Lightness (https://justaddlightness.co.uk). The problem is I can’t justify the cost, specifically of one of the lights that is only there because of legal requirement, and I will only use during its annual road worthiness test.
This doesn’t mean I won’t upgrade them to LED and research the most cost effective and efficient (in my mind) option.
The upgrade is the same for both reverse and fog light, so I am only going to describe one of them. Remove the two screws and pull the lens out to expose the bulb and reflector. Twist the bulb and remove it. Note the position of the bulb locating lugs, this is important for the replacement LED bulb locations.
The bulb I chose is a OSRAM P21W (Red) bulb, because it has two LED chips, one facing the reflector and the other facing the lens to maximise the light emitted from the light. The important thing I checked before choosing this built was that orientation in respect to the reflector.
Assembly is simple, but it‘s worth checking there is no plastic swarf from the adaptation Caterham did when fitting the light in the seal, and the seal and upper reflector are fitted properly. Fit the bulb with a push and twist, and refit the lens and screws.
The only difference between the fog and reverse light is the bulb is white, not red, and the reflector has a matt finish.