How headlights work

Headlight Bulb Replacement

All cars have sidelights and headlights. Older and non-premium cars tend to use halogen bulbs but newer, pricier and plusher models feature bulbs are filled with xenon gas, which gives a brighter, whiter light. These are also known as high-intensity discharge (HID) lights. The high voltages produced by this system can be fatal in the event of a shock, so the battery negative lead should be disconnected before any work is carried out on vehicles with xenon bulbs.

This task requires no experience and few, if any, tools, and will take a matter of minutes to complete.

When to change your headlight bulbs

“Without a full set of functioning headlight bulbs you’re making night-time driving more difficult for yourself”

You need to change a bulb as soon as it blows. Without a full set of functioning headlight bulbs you’re making night-time driving more difficult for yourself and aren’t making your car as visible to oncoming drivers.

You also risk being pulled over by the police and face a possible fine, although you’ll usually be given a few days to replace the bulb (and prove you’ve done it) before facing further action.

What headlight bulb do I need? All cars are slightly different, so if it is time to change your headlight bulbs, find your car for specific instructions.

How to change your headlight bulbs

Here's an example of how it's done. Find the full step-by-step for your model

A very brief summary of the task:

  1. Refer to your Haynes manual to see if the bulb can be replaced with the headlight in situ or if further dismantling is required
  2. If it can be done in situ, open the bonnet. Disconnect the negative battery lead if replacing xenon bulbs. Locate the back of the headlight housing
  3. Remove the cover and locate the blown bulb. You may need to release spring levers and disconnect the electrical connectors
  4. Remove the bulb. Install the new bulb but don’t touch it with your skin. Connect it and replace covers and housing

Why you should change your headlight bulbs

Warning

A blown bulb could get you into trouble with the law because your car won’t be road legal without a functioning set of headlights.

Warning

A poor spread of light as a result of a blown bulb makes driving on any road at night dangerous, but country roads without street lighting are particularly hazardous.

Tools you may need

  • Flat-bladed screwdriver
  • Phillips screwdriver
  • Torx screwdriver
  • Ratchet set

Parts you may need

  • Bulbs
  • Gloves

Warning

Make sure you buy the right type and wattage

How much are headlight bulbs?

Side lights £1
Indicator bulb £1
Single headlight bulb £5-10
Upgraded performance headlight bulb (pair) £20-£40
Garage fee savings £50-£100