Headlight Bulb Burned Out

A single dark headlight is almost always a bulb. Two at once usually means something else — a fuse, a relay, or a switch.

Severity: Medium

What to Do Right Now

Pop the hood and try a new bulb first (look up the bulb number in your owner's manual). Never touch the glass with bare fingers — skin oil shortens bulb life dramatically.

Common Causes

1. Bulb at end of life: Halogen bulbs last 500–1,000 hours. Replace as a matched pair so the beams stay even. Shop headlight bulb
2. Blown fuse: If both sides go dark at the same time, check the headlight fuse in the under-hood fuse box first. Shop fuse
3. Failed headlight relay: Relay clicks when you turn the lights on. No click = bad relay or socket corrosion. Shop headlight relay
4. Corroded socket: Moisture in the housing turns the contacts green. Clean with electrical contact cleaner or replace the socket. Shop headlight socket
5. Yellowed lens cutting output: The bulb may be fine — the plastic lens is so oxidized it blocks half the light. A $20 restoration kit usually fixes it. Shop headlight restoration