Honda Civic Owners Manual: Fogged Exterior Light Lenses

The inside lenses of exterior lights (headlights, brake lights, etc.) may fog temporarily if you have driven in the rain, or after the vehicle has been run through a car wash.

Dew condensation also may build up inside the lenses when there is a significant enough difference between the ambient and inside-lens temperatures (similar to vehicle windows fogging up in rainy conditions). These conditions are natural processes, not structural design problems in the exterior lights.

Lens design characteristics may result in moisture developing on the lens frame surfaces. This also is not a malfunction. However, if you see large amounts of water accumulation, or large water drops building up inside the lenses, have your vehicle inspected by a dealer.