Symptoms
- One rear light doesn't illuminate with parking lights on
- Dash may show a bulb-out warning on newer cars
- Other taillight functions work on that side (brake, turn signal)
- Reduced visibility to traffic behind at night
Likely causes
- CommonBurned out taillight bulbBulbs wear out over time from normal use and vibration.
- PossibleCorroded bulb socketMoisture can get into the taillight housing and corrode the socket contacts.
- PossibleBlown fuse for that side's taillight circuitSome vehicles fuse taillights separately by side.
- PossibleWater intrusion into the taillight housingA cracked lens or bad seal can let water in and damage the bulb or socket.
What to do
- Turn on parking lights and check which specific bulb function is out (parking light vs. brake vs. turn signal).
- Check the fuse box for a blown taillight fuse and replace with the correct amperage.
- Access the taillight housing (usually from the trunk or under a panel) and remove the bulb.
- Inspect the bulb for a broken filament or dark, discolored glass indicating it's burned out.
- Check the socket for corrosion or moisture and clean gently if needed.
- Install a new bulb of the correct type and test all functions (parking, brake, turn signal) before closing up.
- Check the lens for cracks that could be letting water in, which would explain repeated bulb failures.
- Have a shop replace the housing if the lens is cracked or repeatedly lets in moisture.
Tools and parts
- Screwdriver or trim tool (varies by vehicle)
Taillight bulbSearch: “taillight bulb for [your car make model year]”
When to call a pro
If bulbs keep burning out repeatedly in the same spot, have a shop check for moisture intrusion or a wiring issue.
Safety
Use caution
Driving with a taillight out reduces your visibility to traffic behind you, especially at night or in bad weather; fix this promptly.