I have a car that came with yellow Halogen Fogs that are standard in Japan. In Kenya we use fog lights a lot at night because our roads are barely lit even in cities, barely painted. Our roads are full of obstacles from unmarked bumps including mountain ones to potholes.

I tried switching to LEDs (Philips Ultinon Extreme) but when they light wider than Yellow Halogen Fogs such that I can see the end of unmarked roads, they are poor at illuminating the road directly in front, such that I only see obstacles at the very last minute without my full lights.

Visibility seems better after I switched back to standard halogen fogs. I am wondering if this is expected behaviour of the 2.

  • Welcome to Motor Vehicle Maintenance & Repair! I think it all depends on what exactly you get. Some of them (LEDs) are going to work better than others. It depends on how they are made, luminosity levels, color output, etc. If you aren't measuring apples to applies, you can't really say "LED vs Halogen", they just don't match up. Commented Feb 21, 2021 at 16:32

3 Answers 3


Headlights and fog lights have a parabolic reflector that is shaped to shine in a cone ahead of the car, the light source has to be in the right position to focus correctly. Think of a magnifying glass, as you move it closer or farther away from a light source the focus changes, the same principle applies here. Most likely the LED replacement is shorter or longer than your halogen light, so the LED light is father from or closer to the reflector, changing its focus. The technology isn't the issue, LEDs will work fine as long as you get the right one.


Automotive headlights have for the most part historically, designed explicitly with halogen bulbs in mind, as standardized by the Federal Motor Vehicle Safety Standard 108 in the US, Canada and New Zealand, and by the United Nations Economic Commission for Europe (UNECE) for most of the rest of the world. The wiki article on Headlamps is especially informative

Here's an article that helped in my own understanding this question; https://jalopnik.com/why-most-led-headlight-upgrades-dont-really-work-an-ex-1843070472 lots of good links in the article too.

Like @GdD said, LEDs can work as halogen replacements, you just have to find the right bulbs for your particular application.


In case anyone lands here, had to go back to the halogen fog lights. The LEds appear brighter but the halogens have better depth and work better in the dark!

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