Simple techniques for cleaning up foggy headlights

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Close-up of automobile headlight glass that's fogged over with condensation.

Foggy headlights can cause lamp failure or, in the worst cases, accidents. (Photo Credit: CC BY-ND/Dave Linger/Flickr)

If you’re driving at night with fogged over or dirty headlights, you’re risking the possibility of not seeing an obstacle in the road. That can spell a serious accident. Not only that, but if condensation and grime are allowed to sit inside a headlight for a long period of time, the possibility for headlight failure increases. This increases the likelihood of getting a “fix it” ticket from your friendly neighborhood state trooper. Thankfully, it isn’t difficult to deal with this small problem before it becomes a larger one.

Foggy headlights are inevitable

Water enters into the headlight assembly of any car, writes Popular Mechanics. When the mercury falls, the surfaces of your vehicle collect water condensation. That same cool moisture gets into the headlamp mechanism, which is vented to compensate for pressure differences so that cracking doesn’t occur. Generally, when morning temperatures rise, the moisture inside the headlights evaporates. But if it doesn’t – let’s say your car is parked in a shady spot or parking structure – some action may be necessary.

Here’s what you do with foggy headlights

If you have a fancy car, just hit the headlamp defogger button. But let’s assume you’re like the rest of us.

Popular Mechanics’ first suggestion is that car owners do some research to see if a Technical Service Bulletin exists for their make and model of vehicle. That bulletin will reveal whether there is an upgrade available to replace the factory headlight housing (which is generally cheap and inefficient at venting the lighting unit).

If there is no upgrade available, then it’s time for some simple remedies. If there’s only a small amount of condensation inside the headlight fixture, leave the headlights on while you drive for a couple of hours. It’s a great excuse to take the scenic route. If there’s more water in there than a few drops, taking out the headlight fixture may be a good idea. Watch for mud, wasps and spiders while you’re in there cleaning up. Dump the water and critters, add some rubbing alcohol to the housing to clean the surfaces, then let the whole thing dry for a couple of hours in the sun before re-insertion. Finally, Popular Mechanics suggests that you park your car facing south whenever possible to help reduce the amount of condensation that accumulates.

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  1. lovey on

    I have a 2004 trail blazer and the head lights have a brownish film that is hard to get off. What do I do?