CAR’s guide to headlight bulbs

Divert your attention from tedious office tasks with our riveting guide to headlight bulbs.

Headlight bulbs

by Chris Williams |

As the world of automotive headlights (yes, it’s big business), evolves towards increasingly intelligent and adaptive lights, you could be forgiven for thinking the simple days of changing your car’s own bulbs are gone. Not necessarily so. The majority of cars these days still use the old school halogen bulbs, making bulb replacements still possible.

Halogen/Filament

They’ve been around for decades. Halogens use filaments of glowing halogen gas to create their light; modern halogen bulbs are far brighter and longer lasting than they used to be. They use a range of H fittings (for example, H1, H4, H7), so make sure you know which one you need when replacing your own.

Replacement bulbs

The first, natural step is finding out which bulbs your car already has fitted. Please don't be one of the wombles who asks a shop assistant for a replacement bulb without knowing which one; I used to sell hiking footwear and the number of people coming in who didn’t know their own shoe size (predominantly men), was ridiculous.

To check, your car’s user manual should tell you. Alternatively, you can check the actual bulb itself (some cars also have the bulb type on the headlight casing inside the engine bay), or you can go online. There are numerous car parts websites that allow you to plug in your car’s rego or details and the correct bulbs will be presented to you – Amazon does this too.

amazon garage
©Amazon

Halogen bulbs are easy but sometimes fiddly to replace:

1. Access to headlights is from behind, inside the engine bay, don’t have to remove the headlight

2. Designs vary but generally, there will be a plastic cover that you remove to access the bulbs inside the light.

3. Carefully unclip or pull out the bulb from the mounting. And look at the position the bulb was clipped in, so you know how to fit the new one.

Tip: It doesn’t matter with the old bulb but do not touch the glass on the new bulb because your oil on your skin will blow the bulb immediately.

4. Remove the old bulb from the connector.

5. In order to fit the new one, do the exact reverse of steps 1 to 4.

6. Once you’ve fitted the new bulb, give them a test.

Xenon/High Intensity Discharge (HID)

These bulbs have an arc that use xenon gas and metal salts to generate their light. Xenon bulbs require a momentary high voltage to ignite. They burn colder than halogen which is why they emit a bluer light; Xenon bulbs also tend to be brighter and last longer too. Consequently, they are more expensive to buy than halogens. In terms of fitting, xenon bulbs can only be fitted to cars that came with them from the factory; it’s illegal to install them. They use a range of D fittings.

Some xenon bulbs can be replaced in a similar fashion to halogens – it depends on the car model. However, some xenon bulb replacements require removing the entire headlamp, in which case, you can still buy the bulbs to save a few pounds if you wish, but get them fitted by a professional.

LED bulbs

Like HID, are not allowed to be retrofitted on car headlights – you can fit them in interior lights for example. You may find LED lights with H7 fittings for example, but they are not road legal or ECE compliant. LEDs are more energy efficient and long lasting than the competition - up to 10 or so years. These days, LED lights are generally replacing xenon in new cars – for example, current higher-end Mercedes-Benz A Class models feature LED headlights. They’re practical and allow car makers to create cool headlight shapes. LEDs can be fitted with sensors and therefore become adaptive. The downside is they can be incredibly expensive to replace and only done by professionals.

Future of headlights

These days laser lights are coming into the battle. These work by firing a laser at phosphorus, emitting light which is filtered through a lens and then hits a reflector. The advantage is a cool gimmick. Also, this laser light technology uses hundreds of mirrors that can be individually adjusted by the car’s brain to tune where and how the road ahead is illuminated. In simple English: smart adaptive headlights. Cool stuff.

READ NEXT:

Clean airways: CAR's guide to air filters

The car owner's guide to windscreen wipers

The best engine oils

Just so you know, whilst we may receive a commission or other compensation from the links on this website, we never allow this to influence product selections - read why you should trust us