Dim headlights are a safety problem in addition to a nuisance. The cause is usually oxidized lens covers, aging bulbs, a weak charging system, or a corroded ground. Here are the most likely causes ranked by how often they turn out to be the problem.
UV-yellowed plastic lenses cut light output by 40-60%. A $15 restoration kit and 30 minutes restore them like new.
Halogen bulbs dim 20-30% over 2-3 years long before they burn out. Replace in pairs every 2-3 years for full output.
Low voltage at idle dims everything. Check battery voltage with engine running - should be 13.8-14.4V.
A poor headlight ground (often at the inner fender) drops voltage at the bulb. Clean and tighten with dielectric grease.
Off-brand or wrong-spec bulbs often produce less light despite higher claimed numbers. Stick with OEM-spec from a known brand.
Your headlights flicker or go out, the battery light or charge gauge is showing a fault, or you cannot see far enough ahead to stop. Driving with significantly degraded headlights drastically raises night crash risk.
Tell us your symptoms and any codes you have. AmpAuto's AI cross-references NHTSA recall data, common failure patterns, and your exact year/make/model to give you the most likely cause - free, no signup.
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UV damage to the polycarbonate lens cover. A $15 restoration kit (sand, polish, UV sealant) brings them back to clear.
Yes. Bulbs dim with age before they burn out. Replacing one leaves a noticeable brightness mismatch.
DIY kit: $15-$40. Shop service: $80-$150. Lens replacement: $200-$1000+ depending on the car.
Often yes for older halogens, but pick a bulb designed for reflector or projector housing matching yours, or you scatter light and blind oncoming traffic.
Low voltage at idle from a weak alternator or worn battery. Test charging system voltage with engine running.