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Car encyclopedia

Headlight Bulb

On modern vehicles, the headlight bulb is replaceable, while a “sealed beam” design is used on older vehicles. The bulb or “sealed beam” can be filled with halogen gas, which provides better illumination than standard bulbs.

Symptoms of Wear or Failure

  • One or more of the headlights will not operate
  • Discoloration of the headlight lens

Related Repair Advice

  • The most common failure is simply a burned out bulb. However, the repair may be difficult since access to the bulbs can be limited on some vehicles.
  • If one headlight bulb burns out, the other may not be far behind. In many cases, a repair shop will recommend replacing both blubs when one burns out
  • Depending on the model, one bulb may contain both the high and low beam filaments; or, two separate bulbs may be used.
  • Care must be taken when headlight bulbs are replaced so the headlight still aims in the right direction
  • Systems using separate high and low beam bulbs will have the low beam located outboard or above the high beam
  • Some vehicles use high-intensity discharge (HID) or Xenon type headlight bulbs, which can be very expensive to replace
  • Failure of the headlight or high beam switch could also cause the headlights not to function correctly

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