# When to change headlights? **URL:** \ **Category:** General Discussion\ **Tags:** volkswagen\ **Created:** [April 7, 2025, 8:00pm UTC](https://community.cartalk.com/t/when-to-change-headlights/199783 "2025-04-07T20:00:51Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![yayasolete13](https://avatars.discourse-cdn.com/v4/letter/y/a698b9/32.png) [@yayasolete13](https://community.cartalk.com/u/yayasolete13)\ **Post date:** [April 7, 2025, 8:00pm UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/1 "2025-04-07T20:00:52Z")
If you have to change one headlamp, isn’t it best to stagger them and not change the other (working) one until it no longer works? My thinking is that at least you will always have at least one bulb working, right? ---
**Author:** ![lion9car](https://avatars.discourse-cdn.com/v4/letter/l/59ef9b/32.png) [@lion9car](https://community.cartalk.com/u/lion9car)\ **Post date:** [April 7, 2025, 8:06pm UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/2 "2025-04-07T20:06:44Z")
If you change the second one and put the bulb in your trunk as a spare, then you should always have two working bulbs on hand, which is even better. ---
**Author:** ![yayasolete13](https://avatars.discourse-cdn.com/v4/letter/y/a698b9/32.png) [@yayasolete13](https://community.cartalk.com/u/yayasolete13)\ **Post date:** [April 7, 2025, 8:07pm UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/3 "2025-04-07T20:07:16Z")
I like that, thanks! ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [April 7, 2025, 10:50pm UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/4 "2025-04-07T22:50:12Z")
I always just change them as they go out. But I’ve also never had a vehicle where the labor was the same to change just one rather than both. (I’m imagining some weird set-ups where maybe the whole bumper cover had to come off - ? Never had that, but it wouldn’t surprise me). The only other thing I’m thinking about is if you get obviously mis-matched bulbs. This happened to me once when I had to get a replacement assy for a vehicle. I ordered an OEM from a junker online, which came with a working bulb in it. Turned out that the new-used bulb was some manner of bright white while my other was that sort of yellowed out color. I figured I’d change it for that reason. P.S. a couple of years later I still haven’t changed it. LOL. If it ain’t broke don’t fix it. But I will throw working used bulbs (if I have them for whatever reason) in the trunk or glove box (properly packaged to avoid contamination). No reason not to! ---
**Author:** ![bing](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bing/32/4619_2.png) [@bing](https://community.cartalk.com/u/bing)\ **Post date:** [April 7, 2025, 11:58pm UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/5 "2025-04-07T23:58:52Z")
I change them both at the same time for two reasons. The first is that they have an engineered life expectancy so when one goes out the other can’t be far behind. The second is that I have to loosen the upper bumper to get the housing out so it is only a little extra time to change the other one. Thirdly, they alway go out at inconvenient times or places and I would rather control that myself. The ones I buy are $50 for th3 two . ---
**Author:** ![TwinTurbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@TwinTurbo](https://community.cartalk.com/u/TwinTurbo)\ **Post date:** [April 8, 2025, 12:06am UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/6 "2025-04-08T00:06:47Z")
Here’s the thing about lamps with filaments- they wear out. They are consumed as they run and as they are consumed, several things contribute to declining light output over time. If you ever saw the lumens / time curve for such a lamp you’d see they have a steep initial drop before settling into a steady decline toward eventual death. Funny part is, this happens slow enough that most people don’t realize how far gone they are until one burns out and they replace it but keep the other one because it still lights up. That remaining lamp may be at 15% life left in it. If you had two front tires where one wore a bit faster than the other, would you replace only one and then wait until the other one was bare before replacing it? No, they are replaced in pairs for similar reason. ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [April 8, 2025, 12:57am UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/7 "2025-04-08T00:57:02Z")
> [@TwinTurbo](#): > > If you had two front tires where one wore a bit faster than the other, would you replace only one and then wait until the other one was bare before replacing it? No, they are replaced in pairs for similar reason. I’ll call false equivalency on that one. For one, if your two front tires are wearing differently, then you need an alignment - and aren’t doing rotations. For another, headlights have nothing to do with traction. One lets you see the road the other helps your vehicle stay on the road in the manner intended. And on the issue of consumption over time, I get that and I’ll yield to the engineer (i.e. to TwinTurbo). But in all of my 40+ years on the road, I’ve virtually never had the “other” light burn out in short order after replacing one. ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [April 8, 2025, 12:57am UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/8 "2025-04-08T00:57:26Z")
> [@bing](#): > > I have to loosen the upper bumper to get the housing out so it is only a little extra time to change the other one. That’s when I’d just change both. ---
**Author:** ![johnlump\_191311](https://avatars.discourse-cdn.com/v4/letter/j/47e85d/32.png) [@johnlump\_191311](https://community.cartalk.com/u/johnlump_191311)\ **Post date:** [April 11, 2025, 8:55pm UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/9 "2025-04-11T20:55:53Z")
I had a Focus ST with ultra HID lamps. Just the lamp alone was a few hundred bucks. I wasn’t going to buy two if the other still worked. And the other still worked when I sold it years later. Guess it depends on the circumstances. ---
**Author:** ![bing](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bing/32/4619_2.png) [@bing](https://community.cartalk.com/u/bing)\ **Post date:** [April 11, 2025, 10:22pm UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/10 "2025-04-11T22:22:28Z")
Yeah HIDs are a whole nother issue. I only had one go brown and it was replaced under warranty. It should really be a dealer that does it since it could also be the voltage booster that can be dangerous. I was talking standard bulbs. ---
**Author:** ![Old-Days-Rick](https://avatars.discourse-cdn.com/v4/letter/o/7feea3/32.png) [@Old-Days-Rick](https://community.cartalk.com/u/Old-Days-Rick)\ **Post date:** [April 11, 2025, 11:34pm UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/11 "2025-04-11T23:34:35Z")
One thing to as is can you easily change both bulbs, or does it require bumper cover removal or more? If its a vehicle that you can easily chamge the bulvs on, such as my silverado, then id do one at a time, or change both and keep one as a spare. However if its a vehicle that requires a lift to change the bulbs and significant labor, then I’d do both at the same. ---
**Author:** ![johnlump\_191311](https://avatars.discourse-cdn.com/v4/letter/j/47e85d/32.png) [@johnlump\_191311](https://community.cartalk.com/u/johnlump_191311)\ **Post date:** [May 13, 2025, 8:44am UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/12 "2025-05-13T08:44:47Z")
Yes sir. Once I read that they run at about 20,000 volts I let the mechanic install it. ---
**Author:** ![TwinTurbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@TwinTurbo](https://community.cartalk.com/u/TwinTurbo)\ **Post date:** [May 13, 2025, 11:22am UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/13 "2025-05-13T11:22:58Z")
> [@johnlump\_191311](#): > > Once I read that they run at about 20,000 volts I let the mechanic install it. That’s the ignition or trigger voltage required to start the lamp. It doesn’t run continuously at that voltage. Once ignited, the voltage drops to a low DC value, usually from 12-24VDC. Are you hesitant to change spark plugs? Same basic scenario. The ignition coil produces a similar voltage for them to arc over… ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [May 13, 2025, 1:05pm UTC](https://community.cartalk.com/t/when-to-change-headlights/199783/14 "2025-05-13T13:05:50Z")
> [@johnlump\_191311](#): > > Yes sir. Once I read that they run at about 20,000 volts I let the mechanic install it. I’ve never done anything different when changing out a HID light vs any other bulb… lol (other than what is required to access them) Heck, I have never worn gloves of any kind to swap out headlight bulbs either… 😁