Bulbs

Complete lamps or bulbs

Lighting parts come in two kinds. Complete lamps, such as headlights, tail lights, indicators and fog lamps, are shaped for one chassis and its mounts, so they are chosen by car; the car selector lists the ones made for yours. Bulbs fit any car that takes the same type. On older cars whose headlight lenses have yellowed or cracked, a repair lens kit replaces the outer lens and keeps the original housing.

Bulb types and colour

Every bulb has a type code that fixes its base and filament layout, and a replacement must carry the same code. H4 has two filaments, dipped and main beam in one bulb; H7, H11, HB3 and HB4 are single-filament types, each for one beam. Light colour is given as a colour temperature in kelvin (K): the higher the number, the whiter and then bluer the light looks.

Approval marks

Lamps approved under the UN ECE regulations, used across Europe, the UK and many other countries, carry an E-mark: E followed by the number of the country that granted the approval, such as E1 for Germany, E4 for the Netherlands or E11 for the United Kingdom. In the United States, lighting is regulated by FMVSS 108, and headlights must carry the DOT mark on the lens. A lamp without the mark your country uses may not pass a roadworthiness inspection, so check before buying a lamp for road use.

HID and LED

HID and LED light sources are brighter than halogen, but a headlight's reflector or projector is designed around one kind of source. An HID or LED bulb in a headlight built for halogen spreads light where it should not and can dazzle other drivers, and many countries do not accept it for road use. For a road car, choose a complete headlight built for the light source it uses.

LED indicators draw much less current than bulbs, and many cars' flasher relays read that as a blown bulb and flash too fast. An LED-compatible flasher relay, such as Valenti's, or load resistors bring the rate back to normal. Some cars have no separate relay because the flasher is built into a control module; check those before ordering.