Frequent low beam burnout?

Mazda6, 2003, standard model.About 66,000 miles. Just before warranty expiration (15 mos ago), one low beam bulb went out and was replaced by dealer. Since then, we have had to replace one side then the other every 4-6 months. Dealer is a 2 hour drive away so we just replace the bulb for $20.–the cost of gas. I’d just like to know, if possible, the probable causes (beyond electrical/battery?; voltage/battery?; oily bulbs)for these burnouts so that when I contact the dealer, I have some idea of what’s going on so they don’t give me a roundaround. I have searched and searched and can’t see that it’s a usual problem but in forty-five years of car ownership (and we keep cars for 10 years), I’ve never had to replace headlight bulbs. Yeah, just lucky, I quess.Your help is appreciated.

The usual list includes:

  • Touching the bulb
  • Vibration
  • High voltage (should not be higher than about 13.6V with engine running)
  • Poor contacts (including ground)
  • Poor lamps. (Don’t choose fancy blue or extra bright lamps.)
  • While DRL’s do mean that some drivers will be replacing lamps more often than before, it should not mean 4-6 months, unless you are driving nearly all day and night.
  • Have you had any other lamps go out?

Please read the packaging on the light bulb. Do not touch the glass bulb. A strict no-no. This will definitely cause the bulb to blow early. Only touch the plastic outer body. Also, is there any moisture inside the lens housing. This will also kill the bulb early.

The other posters give good possible causes. The voltage at the battery could be higher than normal and cause this. While I would say that 13.6 volts may be a good average voltage it could go up to 14.8 volts an times and still be considered normal. If the battery voltage is within spec, as a best guess to this trouble I think the trouble may be the manufacturer of the bulb, especially, if all the replacements have been from the same source. If they have been from the same manufacturer I would try to find a different source of them.

"* While DRL’s do mean that some drivers will be replacing lamps more often than before, it should not mean 4-6 months, unless you are driving nearly all day and night. "

DRLs typically don’t use the low beams. They generally use the high beam filaments, but at a reduced voltage.

Mechanical shock will kill headlamps as fast as anything else will. Hitting hard bumps at speed, slamming the hood, and even slamming doors can make headlights fail.

Thanks for your advice. We had checked for moisture–negative as far as we can see. The car has been through several south Florida hurricanes so I thought that might be it. I can’t speak for the manufacturer, but when we replaced the bulbs, no contact was made to the bulb itself due to the length of the metal attachment piece. We know that oily residue will get very hot. The initial self-replacement bulbs were different from the OEM bulbs. I went back to the original $6.00 bulb for the last one. It hasn’t been a month yet. The vibration factor may weigh in though I don’t think so. Your voltage parameters give me something to ask for when I get it checked out so I really appreciate it.

Thanks for the list. No other lamps have gone out. I don’t think the dealer replaced the first burnout with a “fancy” bulb, but that’s what my husband purchased for subsequent replacements. I went back to the OEM for the last one. That, or the voltage, seems to be what it may come down to. Mazda had to replace the battery several months before the bulb went out so I believed that all the electrical system would have been checked out at that point.

There should be a rubber seal around the bulb and the clip holding it in place should have some spring action. If either isn’t right, then you would get excessive vibration.