Ask a Mechanic: Shedding light on LED replacements

Dear Ask a Mechanic,

I have a common problem, a burned-out headlight in my 2011 Subaru Forester. I know I need to replace the lights in pairs, but is it possible to replace the original equipment manufacturer halogen headlights with LED ones? I have heard different things about the legality of using LED headlights in vehicles that were not equipped with them from the factory. – Seeking Enlightenment

Although halogen bulbs do lose some of their performance over time, it’s not nearly as pronounced as it was with the sealed beams lights that were common years ago. Replacing them in pairs is not necessary today, though it still a good idea, especially if you have a vehicle that requires major work to access the lights.

With the promise of longer life and a brighter light, LED retrofit headlight bulbs would be a fantastic alternative to the original halogen capsules.

But are they legal? An obvious disclaimer here: I may be automotive savvy, but I’m not a legal expert. Know who likely does have some legal know-how? The legal department at Canadian Tire. The retailer is heavily promoting its Sylvania Zevo line of LED headlight bulbs as an upgrade over the halogen replacements it also carries. This would certainly suggest that they’re not illegal here. Interestingly, in the U.S., Sylvania sells those same Zevo bulbs as intended only for “powersports and fog lamp use.” So, it may be that they’re not legal to use in headlights there.

While this seems like a clear win for the LEDs, I’d still advise against retrofits. In a halogen headlight, the light source is a thin, cylindrical coil of wire, and its precise location and size are strictly defined for each type of bulb. The lamp’s reflector and lens are designed to aim and focus this light to increase its effectiveness and reduce glare.

Most LED retrofit bulbs mount several LEDs on a flat metal heatsink in a position as close as possible to where the conventional filament would be. However, in optics, “close” doesn’t always cut it.

While LED replacement bulbs will work better in some lamps than others, the fudged optics can cause glare for oncoming drivers and beam pattern compromises, even if the overall light quality and quantity appears improved. Also, the fans or cooling fins required by LED bulbs don’t always fit in the available headlight space.

Unless complete upgrade lamps exist for your Forester, cleaning your hazy lenses, using quality halogen bulbs and properly aiming them are the correct ways to optimize your light output.

Ask a Mechanic is written by Brian Early, a Red Seal-certified automotive technician. You can send your questions to wheels@thestar.ca. These answers are for informational purposes only. Please consult a certified mechanic before having any work done to your vehicle.