Honda 2017 Civic Owner's Manual page 584

uuCleaninguExterior Care
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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 light 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.
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