How To Fix A Dim Headlight

This is our guide on how to fix a dim headlight. 

If your headlights appear dim, or if they flicker a lot, it could pose a serious safety risk for nighttime driving. Furthermore, dim headlights can ruin the look of your car. 

Thankfully, there are a couple things you can try to fix dim headlights, depending on what the underlying problem is. 

But before we tell you how you can fix a dim headlight, we must explain what causes headlights to become dim in the first place. 

We have over ten years of practical experience, researching and working on headlights. So if you aren’t sure how to go about fixing a dim headlight, you came to the right place. 

Keep reading for more information on how to fix a dim headlight. 

Why Your Headlight Appears Dim 

There’s a long list of reasons your headlights appear dim or flicker. 

Faulty Bulb

One of the most common causes for dim headlights is a faulty bulb. This could be because the bulb you are using in your headlights is not the correct size or type for your vehicle. 

Or it could be because the bulb was not fitted to your headlights properly. It’s even possible that the aftermarket bulb you bought just turned out to be a dud and you’re entitled to a refund. 

And lastly, if the headlight bulb in question is very old, it could be that it has developed a brownish-gray film on the inside surface that causes it to to appear dim. 

Electrical Issues

Electrical issues that can cause headlights to appear dim range from problems such as frayed wires, stripped insulation, bad conductors, or even an issue with your car’s battery or alternator. 

Excess Condensation In The Headlight 

If there is a lot of condensation build up in your car’s headlights, it could cause the headlights to become dim. 

Besides the moisture interfering with the electrical components, it is also possible that the build up of condensation on the surface of the headlight just makes the light appear dimmer than normal. 

What You’ll Need To Fix A Dim Headlight 

Now that you’ve identified what the problem is, it’s time to fix it. What you need to fix a dim headlight will depend on the exact nature of the problem. 

For example, if a faulty bulb is the culprit, you’ll need a new headlight bulb and an installation kit. 

Alternatively, if the problem is being caused by some wiring issues, you might be able to repair the wire, or you might have to replace that as well. 

As for getting condensation out of the headlight assembly, you could get it done by a professional, or you could do it yourself at home. All you need is a vacuum cleaner, a hair dryer, duct tape and some length of hose. 

How To Fix A Dim Headlight

So now, let’s get into how exactly you should go about fixing a dim headlight. 

Faulty Bulb

When it comes to faulty bulbs that are producing dim light output, you don’t necessarily have to replace the bulb altogether. That may be required, but there are some other problems that might be causing the dim light. 

First and foremost, you should make sure that the bulb is fitted properly. 

Check to see if the bulb fits into the socket as it should, whether or not there are any loose wires, and if there are any tabs that need to be closed for the bulb to fit properly. 

If all is well on the fitment side but you still get dim light, bulb replacement might be the only solution. To replace a burned out bulb, purchase the correct size and type of bulb, any tools you need for the installation, and install the bulb. 

Electrical Issues

Electrical issues will be a bit more challenging to fix than a faulty bulb. If it is frayed wires that are giving you trouble, find the damaged wire and fix or replace it. This might be as simple as wrapping a bit of electrical tape around a frayed wire, or replacing the wire altogether. 

Electrical issues might be caused by a blown fuse. Locate the blown fuse and replace it with the right type of fuse. These are usually color coded, so it shouldn’t be too hard to find a replacement. 

Another common electrical issue might be with the battery or the alternator. It is a good idea to inspect the battery and make sure it is in good working order. This might involve topping up the battery fluid, cleaning oxidation off the battery terminals, or replacing an old battery. 

Excess Condensation In The Headlight 

And finally, if the problem is excess condensation in the headlight, you need to remove moisture from inside the headlight assembly. 

We have made an in-depth guide on how to do this that you can check out, but here’s the…condensed version. 

Take the headlight bulb out of its socket so you have access to the inside of the assembly. Now, connect a hose to the vacuum cleaner using duct tape and place the other end inside the headlight. 

Next, find the headlight vents and position the hair dryer next to the vents. Turn on both the vacuum cleaner and the hair dryer. 

As the vacuum cleaner evacuates the moist air and condensation from the headlight assembly, the hair dryer replaces it with fresh air. 

How To Prevent Your Headlights From Becoming Too Dim

If you want to take some preventative measures to stop your headlights from becoming dim, here is some stuff to keep in mind. 

Keep Up With Regular Battery Maintenance

Keeping up with the regular maintenance of your battery is essential. That means keeping the terminals free of oxidation, keeping the battery fluid at healthy levels, and replacing the battery when needed. 

Prevent Condensation Buildup

There are a couple ways to prevent condensation buildup in your headlights. The first is to make sure that the headlight vents that allow for evacuation of moist air and condensation are not clogged. 

These often get blocked by dirt, road debris, or biological material such as dead insects or mouse droppings. 

Another important measure is to make sure that there are no cracks in your headlight. Small stones, road debris, and the like can strike the headlight, causing cracks which result in higher condensation buildup in the headlight assembly. 

You might even want to invest in a headlight shield made of polycarbonate, or a clear sheet of plastic to prevent the headlight from getting damaged. 

Get The Right Type Of Replacement Headlight Bulbs

It is important to get the right size and type of headlight bulbs for your car. This ensures that the bulbs won’t have fitment issues, won’t draw too much power, and will have the correct wiring setup. 

We recommend consulting the owner’s manual to find out the exact size and type of bulb that you need. And when buying aftermarket replacement bulbs for your car, it is important to do your research and find one that works best for your needs. 

That is why we have also compiled a number of buying guides that can help you make the best choice. 


To sum up, there are a number of reasons your headlights might be exhibiting dim light output. These could be problems relating to the actual bulb itself, the electrical wiring system, or others. 

How you address dim headlights will depend on what exactly the problem is. Some problems can be fixed, while others will require replacing something. 

But no matter the problem, we urge you to get it fixed quickly, as dim headlights pose serious safety risks when driving at night. 

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Richard Nickleson is the author and owner behind Headlight Reviews. He first started the site as a hobby to share his insights on car parts and specifically headlight bulbs, but it soon ballooned and now he writes on all topics surrounding headlights bulbs. If you've got a bulb question, contact Richard here.