One model year can carry three or four different headlights depending on trim, and none of them cross over. Here is how to read yours and match it right the first time.
People say headlight and picture the bulb. The factory assembly is a sealed unit, and one housing holds the lens, the reflector or projector optics, the bulb sockets or LED boards, the aiming adjusters, the mounting tabs that hold everything square to the fender, and on many vehicles a fair amount of electronics: an HID ballast and igniter, an LED driver, a leveling motor, or on adaptive units a swivel motor and its own control module.
That is also why the federal standard treats the whole assembly as the product. Under FMVSS 108, DOT certification applies to the complete headlamp, housing and optics and lens together, not to a lens sold by itself.
Three light sources cover almost everything on the road. Halogen units run a replaceable bulb behind a reflector bowl or a small projector. HID or xenon units burn a D-series arc bulb, need a ballast to strike it, and usually come with automatic leveling because of how bright they are. LED units use fixed arrays that are not serviceable on their own, so a dead segment normally means the whole assembly.
Adaptive systems add motion. Subaru calls its version Steering Responsive Headlights, and most other brands use some form of AFS, adaptive front lighting. The low beams pivot with the steering so the light goes where the road goes, which means a swivel motor, a position sensor, and usually a module inside the housing. All of it has to work in a replacement.
The OEM part number is molded into the back of the housing or printed on a label near the bulb access door. On Japanese-built units you will usually find the lamp maker's own number too, Koito, Stanley, or Ichikoh, which is not the number in the vehicle catalog. Write down both. Fitment gets matched on the vehicle number. The lamp maker's number tells you whether two housings that look identical really are.
The lens carries the lighting identification code, molded in per SAE J759, alongside the DOT mark. Molded rather than printed, so it survives twenty years of road grit. Most housings also carry a date wheel, a molded clock with a year in the middle and an arrow pointing at a month. That is when the housing was made, and it is the quickest way to tell whether a unit falls before or after a mid-year revision.
Side is written the way the parts world writes it. LH is the driver side on a US-market car, RH is the passenger side, and the reference point is the driver's seat rather than the view from the bumper. Plenty of housings have an L or an R molded in near the part number. Send us a photo of the back of your old lamp. The part number and the side settle a match faster than any year-make-model search.
Headlights hold no crash data, so nothing here involves a reset. Coding is another matter.
On most Toyota, Honda, Chevrolet, GMC, Ford, and Nissan vehicles running halogen or basic LED lamps, a replacement assembly plugs in and works. Where the assembly carries its own control electronics, it changes. BMW treats left and right headlights as separate control units, the frontal light electronics modules, and a swapped unit generally has to be coded to the car with factory software before the LEDs light at all. Audi, Volkswagen, and Mercedes matrix and multibeam units follow the same pattern. Line up the coding before the old lamp comes out.
Aiming applies to every headlight, coded or not. Each assembly has a vertical adjuster and often a horizontal one, and a lamp bolted in but never aimed throws light into the trees or into oncoming drivers' eyes. On vehicles with automatic leveling, the level sensor may need initializing afterward. Ten minutes against a garage wall at the right distance, or a shop with an aiming board, separates a headlight that works from one that is a hazard.
The optical reason is aging. Polycarbonate lenses haze and yellow under UV, and HID and LED sources shift color and lose output over the years. Put a clean recycled unit next to a nine-year-old lens on the other corner and the difference is obvious from the driver's seat and from oncoming traffic. If the surviving lamp is badly hazed or fogged, buy the pair.
The electronic reason applies to the higher-end systems. Some manufacturers specify that both units be the same light class and be replaced together, and the coding is done per side as separate control modules. Mixing revisions on those cars produces faults that are miserable to trace.
Light source is the big one. Halogen, HID, and LED versions of one model year are not interchangeable. Different connectors, different power, different modules. Subaru is a clean example: on 2015 to 2019 Legacy and Outback, the halogen, LED, and Steering Responsive versions are three separate parts and none cross over. Silverado and Sierra split the same way, halogen on the work trims and projector HID or LED higher up.
Facelifts split generations mid-stream. A truck that ran seven model years often got a new front clip halfway through, and headlights do not cross that seam even though the model name never changed.
Then the small ones. LED daytime running lamp versus non-LED within the same trim year. Amber turn indicator versus clear. Auto-leveling versus fixed. Any of those hands you a housing that bolts right in with a connector that does not match or a function that never comes on. Body style matters on shared platforms too, since sedan and hatchback versions of one nameplate often use different lamps.
Headlights are the one thing we sell that has nothing to do with the restraint system, so there is no special handling beyond packing for the trip. They are bulky, and the lens and tabs are the fragile parts, so they go out with the tabs supported and the lens face protected. Ground shipping to the lower 48 states, same as the rest of our parts.
Installation is realistic DIY work on most vehicles. Access usually means pulling the grille, bumper cover, or wheel liner, then three or four bolts. Photograph the connector routing before you unplug anything, and aim the lamp when you are done. On a car with coded headlight modules, schedule the coding before you start.
Returns on headlights work differently than on restraint parts. Call 501-988-0611 first and we will tell you whether a return applies and how to send it, instead of you shipping a large box back on a guess. The full policy is on our returns page. To see current inventory, search the parts store for headlights. If your lamp is not listed, call with the number off the old housing.
On most Toyota, Honda, Chevrolet, Ford, and Nissan vehicles with halogen or basic LED lamps, no. On BMW, Audi, Volkswagen, and Mercedes vehicles where each headlight carries its own control module, yes, and the coding is done per side with factory-level software. Sort that out before you order.
Not usually. Two situations make it the better call: the surviving lens is badly hazed or fogged internally and will look and aim different from a clean unit, or your vehicle is one of the higher-end systems where the manufacturer specifies matched light class and paired replacement.
Read the part number off the back of the housing and compare it to the listing. Failing that, look at the bulb. A halogen unit has a removable bulb behind a rubber or plastic cap. An HID uses a D-series bulb with a ballast attached to the housing. An LED unit has no serviceable bulb at all. The three are not interchangeable within the same model year.
Left hand, meaning the driver side of a US-market vehicle, with the reference point being the driver's seat and not the view from the front bumper. RH is the passenger side. Many housings have an L or an R molded in near the part number.
Call 501-988-0611 before you ship anything back. Headlights are not safety restraint parts, so they are handled case by case rather than under the final-sale rule that covers airbags, belts, and modules. We will tell you on the phone whether a return applies and how to send it.
Other parts in the catalogue:
Driver airbag: the module in your steering wheel Passenger airbag: the module behind your dashboard Knee airbags: what they do and how to buy the right one Side curtain airbags Seat side airbags Seat belt retractors All part types
Our staff has handled these parts since the nineties.
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Do not see it listed? Request a part or call 501-988-0611.