How to replace a headlight globe

How to replace a headlight globe

Functioning headlights are essential for driving a car safely, but as we all know, globes only have a limited lifespan. Knowing how to change a headlight globe therefore is a handy skill to have, and one that can save you money – both from expensive mechanical labor charges or a potential fine.

In this blog, we take a look at some of the best tips and tricks for changing a headlight globe yourself, and what to look for when the lights go out!

How do I know if my headlight globe is blown?

Determining whether a headlight globe is blown is as easy as turning on your headlights and walking around to the front of the car. If only one headlight is illuminated, it means the globe has reached the end of its life and needs to be replaced.

It’s recommended that you always replace both globes at the same time. As we mentioned, globes have a limited lifespan, and you can guarantee that if one has failed, the other won’t be far behind. So save yourself the effort and change both globes at one. It also pays to keep a spare set of globes on hand as they often fail without warning.

What causes headlight globes to stop working?

One of the most common causes of headlight globe failure is old age. Headlight globes have a limited lifespan, and with fine inner workings known as filaments, are susceptible to stress from vibration, temperature extremes, moisture, and even oxidization or cracks in the globe’s insulative housing.

What’s also important to know is that headlight globes can fail because of uneven heating of the glass itself. The primary cause of this is from the oils in our fingers leaving residue on the glass that heats at a different rate to the remainder of the globe which then causes a crack - so wear gloves if possible and never touch the glass with your fingers.

Which headlight globe is right for my car?

Knowing which headlight globe fits your car is as simple as opening your car manual. Your owner’s manual will list the headlight globe – and indeed every other globe your car requires – by a letter and number combination known as ‘category type’. Common examples may include H4, H7, D2S, or D3R.

The manufacturer will also specify a voltage and wattage for each globe which is listed by a numerical value followed by the letter V (for volts) and W (for watts) in each instance. Typically, this descriptor will look something like this: 12V 60/55W or 12V 55W.

If you don’t have your car’s owner manual, you can also find the information stamped into the metal body of the globe or ask at the service counter of your local auto parts store.

Are headlight globes and headlamp bulbs the same thing?

Like many automotive parts in use throughout the world, headlight globes are sometimes referred to by other names. These may include headlight or headlamp bulbs, Halogen globes, HID globes and LED globes. And while the terms headlight and headlamp, and globe and bulb are interchangeable, the type of globe used is generally specific to your car.

That’s not to say that some cars fitted with Halogen or HID headlight globes can’t be upgraded to LED globes. But in some instances, this process is more difficult than simply swapping like for like.

How do I replace a headlight globe?

Once you’re ready to change your blown headlight globe, be sure your car and headlights are switched off, and that your headlights have had time to cool down. Headlight globes become hot to touch when operating, and to avoid burnt fingers we recommend you wait five minutes after use before attempting to change your headlight globe.

Next, open the hood of your car and locate the headlight globe on the back of your headlight. If you need help to see what you’re doing, then a flashlight or under-hood work light might come in handy. Some headlights will have a plastic dust cap or rubber boot in addition to a wiring connector. You will need to disconnect the wiring connector and any cap or boot to access the headlight globe.

From here it’s a simple case of pushing down the wire clip or plastic retainer that holds the headlight globe in place or rotating the globe a quarter turn to remove it from the socket. If you’re unsure of how to do this, we recommend referring to your car’s owner manual as some manufacturers use different restraining mechanisms to others.

Retract the blown globe and install the new globe following the same steps above but in reverse. Remember not to touch the glass part of the globe when changing it, and to check that all dust caps, rubber boots and wiring are installed in the same orientation as they were removed.

What do I do if the headlight still doesn’t work?

Remembering what we learned earlier (assuming you’ve followed all the steps so far), you should now be able to see both headlights functioning properly when switching on your headlights and walking to the front of the car. If the globe (or globes) you’ve just replaced aren’t functioning, you might have other issues at play.

The first thing to check – with your headlights and engine switched off, of course – is that nothing you’ve just done is the cause of the issue. Check that the wiring is reconnected properly, that the globe is sitting correctly in its housing, and that any dust caps or rubber boots are securely in place. If that doesn’t resolve the issue, you may need to look a little further.

From here we recommend you check that your fuses are intact and replace any fuse that has blown. If one headlight is working and the other isn’t, then a blown fuse is not the cause of your woes – and this is where things get tricky.

For must of us the steps beyond this point are best left to an auto electrician or mechanic. You could have damaged wiring, a broken connector, or water in part of your car’s electrical system that is causing other issues. In most cases these are not an expensive fixes and will be far cheaper than the fine for driving with only one functioning headlight.

Can I replace my headlight globes with brighter globes?

New technology including HID and LED headlight globes mean it’s now possible to purchase globes that are brighter than the original headlight globe without needing to modify your car’s electrical system. But the list of which globes fits a certain car, how much power it draws, and how hot it might get inside the headlight unit, are all considerations most of us need assistance to determine.

It's also really important to know the law relating to headlight output in your particular state or territory. In some parts of America, it’s illegal to fit a brighter globe than is recommended by the manufacturer. Although this is very hard to police, a fine and an unroadworthy car is a hassle most of us could do without. We always recommend checking your state or territory’s guidelines before uprating your headlight globes or installing additional lights (e.g.: driving lights or fog lights).