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Do headlights dim as they age?

2006 Nissan Sentra

Recently, I noticed I can’t see any light on the road when the headlights are on or very dim. I have never replaced the bulbs since I acquired the car pre-owned in 2010. If I tun the high beam on, I can see the light on the road. Hence the question, do these bulbs get dim as they age?

I am not too sure what kind of lights are these but I assume they are halogens.

Bulbs dim some, but the biggest change is the lenses fog up. Are yours anything beside crystal clear? Also the reflectors can deteriorate. Lenses can be polished, reflectors can’t.



I use the Silver star and it seemed like every December they would need replacing, so I bought a new set for $50 in anticipation. Still hanging there on the bench and it’s almost two years now. Maybe I should just put the new ones in now.

Be sure to buy another set when you change them. If you don’t, they will go back to fading quickly.

Back 40 years or so ago, when conventional incandescent bulbs were replaced with halogen incandescent bulbs, one selling point was that the halogens would not dim with age. Supposedly, they would run at 100% brightness until the day they burned out. That turned out not to be true.

A lot of the rave reviews that we see on headlight bulbs are actually the result of comparing brand new bulbs to old bulbs.

HID bulbs don’t seem to dim at all because they use an arc rather than a hot filament. BMW HIDs tend to roast the finish off their reflectors after 10-15 years.

I’ve only had one HID go out and it turned to a purple hue or something, best I can remember. They wouldn’t replace it under warranty until it went completely out. After turning color, it only took a month or so before it went completely out. So it didn’t really dim but just turned color. I don’t know if they all do that though.

My vehicles are both older & equipped w/ standard halogen headlights. I’ve never noticed the headlights dimming. Until they burn out completely that is. The only dimming I’ve noticed is a newly installed headlight may dim somewhat in the week after installing, but not much that I’ve noticed after that.

If you got some dimming going on and there’s nothing blocking the light output (as mentioned above), then ask your shop to measure the voltage on the light bulb’s contacts when it is turned on. It might be lower than the battery voltage because of corrosion on the contacts or the grounds-to-chassis. Measure the battery voltage too of course. Should be 13.5 volts or above when the engine is idling. A battery or alternator on the way out could show up as headlight dimming.

Just make sure it’s not your eyes dimming.

All lamp technologies degrade over time. Filament and arc lamps have a hockey stick like degradation curve. Filament lamps have steepest initial drop and shortest life. LEDs have essentially linear loss slope from initial turn on to failure.

It’s like cataracts, you don’t realize it’s getting dimmer until a threshold is reached and you suddenly notice how terrible it has gotten.

This is repeating some of the information above, but I’d put in new bulbs, polish the outside of the lenses with a headlight restoration kit such as the one from Meguiar’s (keeping in mind that the problem might be on the inside of the lenses, in which case this won’t help), and make sure the lights are aimed correctly.

+1 At age 25 my vision was 20/10 and night vision noted as superior. 20 years later both had noticibly deteriorated which has continued over the next 20 years.

Vision is not the only problem at 65. At this age, everything either dries up or leaks.

How very true. LOL

Oh to be 65 again.

Me too. I will be 66 1/2 next month.