What causes car headlights to go out?

1. Old age

The most common culprit for a burned-out light is age, says Zullo. “You could be driving and not notice that one of your headlights is out, and then, since the other one is the same age, within weeks that one might just go bad, too,” he says. Suddenly the problem becomes scarily apparent.

2. Extreme cold and heat

Besides age, extreme cold or heat can also cause headlights to burn out. The changes in temperature can impact the lightbulb filament, which is very delicate.

3. Oxidation

With newer halogen bulbs, another cause of dimming lights can be oxidation of the plastic housing, causing it to appear white or yellowish, Zullo says. This diminishes the beam of light that helps drivers to see the dark road ahead, he says. “In that case, you would have to replace the whole headlight assembly,” he adds.

4. Cracks in bulb housing

In addition, any cracks in the housing can cause halogen bulbs to burn out because these can’t take any moisture. “So you could put a new bulb in there and within a day or two it will blow out because of the humidity and the wetness,” Zullo says. “Also, these bulbs cannot be touched by your fingers; if you’re installing it, you have to use rubber gloves because if you put your finger on the bulb the salt from your sweat will burn that bulb right out.”

Have a safety plan in case your headlight burns out while driving. Make sure to practice safe driving when you’re on the road.