Should I replace headlight bulbs in pairs?

Yes, for halogens. The other bulb is the same age and will typically follow within months, and a matched pair keeps the beam color and brightness even side to side. Keep the still-working old bulb in the glovebox as a spare.

Can I put LED upgrade bulbs in halogen housings?

Skip them. A halogen housing is shaped around a halogen filament, and an LED bulb in it scatters light everywhere — glaring oncoming drivers while lighting the road worse. They are also not road-legal in most US states, whatever the product listing claims.

Why did my new bulb die within a month?

Three usual causes: skin oil left on the glass, a bargain-bin bulb, or a charging system overcharging and cooking the bulb. The first two are common and cheap to avoid. If good bulbs keep dying, have a shop test the alternator's voltage output.

How do I know which bulb to buy?

The bulb chart in the owner's manual, or the code stamped on the old bulb's base — H11, 9005, H7, and so on. Low and high beams are often different types on the same car, so check which one actually failed before you buy.

How to Replace a Headlight Bulb

About 20 minutesModerate5 steps

A burned-out headlight is a ticket and a safety problem, and on most cars the fix is a $15 bulb and twenty minutes. The hard part is access: some bulbs twist out from behind the housing, others sit behind the battery or an airbox. One rule matters above the rest — never touch the glass of a halogen bulb with bare fingers.

Work with the lights switched off and the bulb cool — halogens run hot enough to burn skin. Many modern cars use sealed LED units that are not owner-serviceable; if there is no bulb to twist out, stop there. Never force a connector or clip — a broken housing tab turns a $15 job into a several-hundred-dollar one.

What you'll need

Correct replacement bulb (the manual's bulb chart or the code on the old bulb's base — H11, 9005, H7; do not mix up types)
Nitrile gloves or a clean cloth (skin oil burns halogen glass)
Screwdriver or trim tools (only if your car needs covers or brackets loosened for access)
Rubbing alcohol (in case you touch the glass)