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Today, most manufacturers make vehicle headlights out of plastic or polycarbonate instead of glass. The reason is that cars come in different shapes and sizes, and so do their headlights. As such, polycarbonate has become the ideal option because it’s durable, lightweight, and moldable into various shapes.

Still, your car’s headlights can turn cloudy and yellow over time, and you might not notice the gradual change. But the problem can become a huge car safety issue that can endanger you and others. It can also get you in trouble with the law. 

How headlights become cloudy or yellowed

Cars with their headlights on drive on a cloudy morning in November 2018
Car headlights on a cloudy morning in November 2018 | Jan Woitas/picture alliance via Getty Images

First, note that cloudy or yellowed headlights decrease visibility, and it’s dangerous to drive with such. Here are some of the reasons why headlights turn foggy or yellow after some time.

Water vapor

High moisture content in the air creates vapor inside a vehicle’s headlight box. The water vapor remains trapped as the air outside becomes drier. In turn, that causes a scattering of the light coming through polycarbonate lens, creating patterns and diffusion of light on the road. And it ultimately impairs your visibility.


The exposure of headlights’ polycarbonate lenses to the air causes oxidation. When that’s the case, lenses develop microscopic cracks, making headlights cloudy.

Dirt and chemicals

A thin layer of chemicals and dirt develops over headlight lenses when a car is on the road for some time. Because the coating is cloudy, it dims the lights and makes the road harder to see at night.

Road damage

Gravel, pebbles, and other debris can fly up onto your headlights when you’re driving on poorly maintained roads. That debris creates pits and dents in the lenses, causing them to become foggy or yellow.

Why driving with yellowed or cloudy headlights is so dangerous

Your vehicle’s headlights should allow you to drive without difficulties at night. That proves a challenge when they turn cloudy or yellow, causing them to generate only 20 percent of the amount of light you get from new headlights. As such, foggy or yellow headlights subject you to dangerous night driving situations. The decreased visibility is a result of damage by sunlight to protective plastic coatings.

Over time, such damage causes discoloration, diminishing headlights’ ability to provide enough light in the dark. It’s also worth mentioning that most road crashes occur at night. For that reason, checking your headlights for signs of deterioration and investing in new ones or low-cost services to improve the safety of driving at night is critical.

Ways to restore cloudy headlights

Modern headlights seem almost too bright when brand new, and like nearly everything on and in a vehicle, they need maintenance as well. Additionally, replacing yellow or cloudy headlights is unnecessary, which is not the case with broken or burned-out car light bulbs. That’s the case because you can clean and restore cloudy or yellow headlights using the right tools.

You can get rid of condensation in headlights by using a hairdryer or silica gel packets and a rag. Also, avoid breaking the seal between the rest of the car and the headlight assembly. This is possible by wiping off the inside of the lens after removing the bulb. After that, get rid of any spiderwebs or debris that could be blocking the assembly vents and replace dried-out, degraded, or cracked O-rings and seals.

On the other hand, you can restore foggy headlights using bug spray or WD40. But it’s a temporary solution, AAA says. That’s because when such products wash away, the problem sets in once again. Also, bug spray with DEET can damage headlights further, in addition to making them sticky. The solution is to sand, polish, and reseal your car’s plastic lenses, which truly restores cloudy and foggy headlights.


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