(Updated on October 20, 2022)
You go outside one morning to start your car and you notice condensation or fog in your headlight. It’s totaled, right? Well, not quite.
There are several reasons you could have condensation, water, or fog in your headlight. Some of these are perfectly normal occurrences and no cause for concern.
What Causes Condensation Inside a Headlight?
If you notice condensation in your headlight after rain or a foggy day, this may be a perfectly normal occurrence if you only notice it occasionally. Sometimes you may also get water in the headlight after a car wash.
There are a few components in your headlight assembly that could allow moisture into your headlight assembly regularly if they go bad.
1) Bad Headlight Seals
Headlights typically use rubber seals or gaskets to keep dirt, water, and debris out of the headlight housing. As a vehicle ages, the rubber on these seals may deteriorate. This could lead to a very tiny leak that allows condensation into the headlight housing.
2) Clogged Headlight Vents
Most headlights heat up when you use them. Warmer air has a lower density than colder air. Headlights contain small vents that allow air pressure to equalize between the interior and exterior of the headlight housing.
Since these vents allow air to pass into the headlight, sometimes water may get in there too.
If the interior and exterior of the headlight cool at different rates, this may leave you with condensation on the inside of the headlight. It’s a bit like taking a cold drink out of the fridge and setting it on the counter. Eventually you will start to see water on the outside of the container.
3) Cracked Headlight
A crack in the headlight may expose the inside of the headlight housing to even more moisture than normal. This depends on how big the crack is, and if that crack is deep enough to go all the way through the plastic housing.
Is Moisture in a Headlight Bad?
Generally a little moisture, fog, or condensation in the headlight is no big deal. This happens occasionally, but may happen to you more frequently depending on your local weather and climate.
If you start to notice water pooling at the bottom the headlight, this is something you may want to address. This typically only happens with bad cracks in the headlight housing or a leaking headlight gasket.
Excess water in the headlight can cause corrosion to wires or other connectors inside the headlight housing.
Will Condensation Go Away On Its Own?
Many times the condensation will go away on its own when the weather changes. Condensation may also disappear when you start driving the car with the lights on.
If the condensation does not go away on its own, it may be time to figure out how to fix the headlight so it doesn’t happen anymore.
How to Remove Moisture From Headlights
1) Clean the Headlight Vents
Sometimes headlight vents can get clogged with debris that prevent them from venting properly. Try removing the headlight assembly and cleaning these tiny vents. This alone may cure the problem, and the fix is free.
2) Replace the Headlight Gasket
On some vehicles, there is a way to disassemble the headlight housing to replace the headlight gasket. If your car is more than 10 years old, this may a good course of action.
This is especially true if your vehicle sat out in the sun for many years. The sun has a way of cracking and drying out rubber components.
When you pull the headlight housing to replace the gasket, make sure to dry out any moisture you find using a hair dryer or a heat gun. If you use a heat gun, be careful to keep your distance so you don’t accidentally melt any of the plastic.
3) Replace the Headlight Housing
Sometimes the headlight housing is damaged beyond repair. In that case, you are probably best off replacing the entire housing. This may be true if the plastic is cracked in a way that compromises the seal and allows additional water into the headlight.
4) Install a Breather Vent
If all else fails, you may be able to install a special breather vent into your headlight housing that allows moisture to exit the housing, but keeps moisture from coming in.
What If There’s Standing Water in the Headlight Assembly?
If you notice standing water inside your headlight, you may notice more corrosion in the headlight assembly over time. This is particularly true if you live near the ocean or in an area that salts roads in the wintertime.
If you start to notice corrosion inside the headlight, it’s best to get the issue addressed right away. Corrosion only gets worse over time.
When Is Headlight Replacement Necessary?
Headlight replacement is usually only necessary if there is a problem with the housing or excessive damage. Most headlight bulbs and gaskets can be replaced without replacing the entire housing.
Water in your headlight isn’t the end of the world. There are some simple steps you can take to correct the issue, and it may not even cost you money to fix the problem.
Some areas of the country are more prone to foggy headlights than others. Ask your neighbors if they have any good solutions for keeping the fog and condensation out of their headlights. They may have a trick to make it even easier.