Is Condensation Inside A Headlight A Serious Problem Or A Harmless Quirk?

Only bright and functioning headlights can transform a lonely stretch of road into a safe place for a moonlight cruise. If you notice water beading on the inside of the lenses, it's natural to feel alarmed since there are such delicate electric components responsible for producing the light you need to drive by. Find out why headlights produce condensation and what to do about the problem.

Why Headlights Fog Up

First, don't let condensation panic you because it can happen with any headlight assembly and doesn't indicate a problem like a cracked housing or leak around the lens. All types of lights can eventually show beads of moisture on the inside of the lens, although halogen lamps tend to develop condensation faster and evaporate it away sooner than LED models. This is due to the extra heat produced by halogen bulbs, which speeds up the condensation and evaporation cycle inside the housing.

The Moisture Source

If condensation isn't caused by a leak, then how does the moisture enter the sealed housing? The moisture is actually trapped during manufacturing since many of the parts inside the housing, including the lens, are made from plastic that absorbs and holds humidity from the air. At some point later when the car is in use, the heating and cooling cycles of the lamps draw out the moisture and cause it to condense on the interior. It can takes years for the moisture to finally appear.

Leaks Vs. Condensation

Not convinced that your moisture issues aren't caused by a leak? Check out the headlight for signs of a leak like

  • Pools of moisture gathering at the bottom of the housing
  • Large droplets of water gathering on the lens rather than a fine and even mist of condensation
  • Obvious tracks of movement from a leak point to a central puddle or pool.

In most cases, moisture inside a headlight is just a normal part of life and not a problem. However, genuine leaks or condensation that worsens over time can cause corrosion and electrical shorts inside the light and should be handled by a professional.

Solving the Problem

If you even suspect a leak, let a professional test the light housing and plug up any cracks and holes with an automotive sealant. A shop like The Dyno Shop can help.

Annoying but harmless condensation can be dealt with on your own. Remove the entire housing and remove the wiring and bulbs, then use a hair dryer or oven running below 180 degrees F to dry the moisture out.