How Headlights Work

Headlight Bulb Replacement

All cars since the 1920s have had electric headlights. Older and lower priced models use halogen bulbs (or standard incandescents) but recently, especially in higher end cars, high intensity discharge (HID), or bi-xenon lights have been used. Another recent innovation is the LED headlight, which uses less power, runs cooler, and could conceivably last the life of the car. 

HID lights give brighter, whiter light, but require high voltage and a ballast to boost the voltage at start up, then taper it off. The high voltage produced can be fatal in the event of a shock, and power remains in the system even after it is turned off and the battery disconnected. For your safety, we don’t recommend that you service HID lights yourself. Instead, have this service performed by a dealer service department or qualified repair shop.

But, the vast majority of cars on the road built in the past 30 years have easy to replace halogen or incandescent bulbs. This task requires no experience and few, if any, tools, and will take just a matter of minutes.

Every car is different, so find your manual for the full instructions...

When To Change Your Headlight Bulbs

“Without a full set of functioning headlights you’re making night driving more difficult for yourself”

There is little need to change a bulb before it blows, but you do need to change a bulb as soon as it blows. Without a full set of functioning headlights you’re making night driving more difficult for yourself and unsafe, as your car isn't as visible to oncoming drivers.

You may want to change bulbs on an older car, just to try some of the news, brighter bulbs now offered. The quality and quality of light from a bulb does diminish with use, but the latest halogen bulbs manage to produce better light and more of it than even a brand new bulb from years ago.

All cars are slightly different, so if it is time to change your headlight bulb, use our before you begin checklist, and find your car for specific instructions.


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. Check all your lights before a long road trip.

Why You Should Change Your Headlight Bulbs

The answer for most people is going to be, because one of them burned out. But there are valid reasons to change bulbs that still work, especially on older cars. For really old vehicles, with incandescent seal beam bulbs, an upgrade to halogen lights is probably a good idea. Even for cars from the 1980s and 1990s, there are better, brighter bulbs out there thanks to advances in chemistry and glass, so an upgrade may be in order. Older bulbs put out less light over time, but the change is so gradual you may never notice it; so you may just want to put new bulbs in after 5 years of use.

Don't forget, when a bulb goes out you risk being pulled over and ticketed by the police, although you’ll usually be given a warning and a few days to replace the bulb (and prove you’ve done it). But it is usually so easy to change the bulb, why risk the hassle?

How To Change Your Headlight Bulbs

This video is a general guide. Find the full step-by-step instructions in your manual.

How To Change Your Headlight Bulbs

A very brief summary of the task on most cars and trucks made since the 1980s:

  1. Open the hood and locate the back of the headlight housing.
  2. Remove the rear cover from the blown bulb. You may need to release spring clips and disconnect the electrical connectors.
  3. Twist the socket/bulb holder counter clockwise 1/4 to 1/2 turn until it releases.
  4. Replace the blown bulb with a new one, being careful not to touch the glass.
  5. If you do touch the bulb, wipe it clean with glass cleaner to prevent premature failure.
  6. Replace socket and turn to lock in place.
  7. Connect electrical connectors and replace covers and housing.
  8. Refer to the full Haynes steps to see details for your specific model.

Before You Begin

Tools you may need

  • Flat-bladed screwdriver
  • Phillips screwdriver
  • Torx screwdriver


Make sure you buy the right type and wattage replacement bulb.

Parts you may need

  • Bulbs