Why headlight aim matters and when to adjust
Headlights that point too high blind oncoming drivers. Headlights that point too low leave the road ahead dark. Either way, you lose visibility and create a safety hazard. Most cars need a headlight adjustment once or twice a year, especially after hitting a pothole, replacing a bulb, or getting new suspension work done. Some states require headlights to be aimed correctly during inspection.
You can adjust most headlights yourself using the adjustment screws behind the headlight housing. The process takes 15 to 30 minutes per side and requires only a screwdriver and a flat wall or garage door. If your car has automatic leveling headlights (common on newer vehicles), the system adjusts itself as the suspension moves, but you may still need to reset it after collision damage or bulb replacement.
Key Takeaways
- Headlight adjustment screws are usually located behind the headlight housing, accessible from inside the engine bay or wheel well.
- You can test aim by parking 25 feet from a wall, turning on low beams, and checking whether the light beam center is at or slightly below the height of your headlight.
- Vertical adjustment screws move the beam up and down; horizontal screws move it left and right.
- If your headlights are severely misaligned after an accident, a professional alignment check is safer than guessing.
Locating the adjustment screws on your headlight
Open your hood and look directly behind the headlight housing you want to adjust. You will see either two or three screws protruding from the back of the housing. One screw controls vertical aim (up and down), one controls horizontal aim (left and right), and some housings have a third for fine-tuning. Your owner's manual will label which is which, or you can identify them by turning each one slightly and watching the beam move.
On some vehicles, you access the screws from inside the wheel well rather than the engine bay. If you cannot see them from behind the headlight, check your manual for the location on your specific model. Older vehicles sometimes have adjustment screws on the outside of the headlight housing itself, visible without opening the hood.
Setting up a test wall and measuring beam height
Park your car on level ground 25 feet away from a flat wall, garage door, or white sheet. Turn on your low-beam headlights and turn off all other lights. The wall should be dark enough that you can see the light pattern clearly. Mark the center of each light beam on the wall with tape or chalk.
The correct aim point is at or slightly below the height of your headlight. If your headlight is 30 inches from the ground, the beam center should hit the wall at 30 inches or slightly lower—no more than 2 inches below. The beam should be centered left-to-right on the car's centerline. If both beams are too high, too low, or off to one side, you have found what needs adjusting.
Adjusting vertical aim with the up-and-down screw
Locate the vertical adjustment screw (usually the top or bottom screw on the headlight housing). Using a screwdriver that fits the screw head, turn it clockwise to raise the beam or counterclockwise to lower it. Make small quarter-turn adjustments and check the wall after each one—the beam moves more than you might expect.
Once the beam center is at the correct height on the wall, move to the horizontal adjustment. Do not skip this step even if vertical aim looks good; a beam that is too far left or right will still reduce visibility and annoy oncoming drivers.
Adjusting horizontal aim with the left-and-right screw
The horizontal adjustment screw is usually positioned to the side of the headlight housing. Turn it clockwise or counterclockwise to move the beam left or right until the center of the beam aligns with your car's centerline on the wall. Again, use quarter-turn adjustments and recheck the wall between each one.
When both the vertical and horizontal aim are correct, step back and look at the overall beam pattern. The light should form a clear cutoff line at the top (so it does not blind oncoming traffic) and should be brightest in the center of your vision when driving. If the pattern looks uneven or the cutoff is jagged, the lens or reflector may be damaged and the headlight may need replacement rather than adjustment.
Checking your work and adjusting the second headlight
Turn off the headlights and move your car 25 feet back from the wall. Turn the low beams back on and look at both beams together. They should be at the same height and brightness. If one is noticeably higher or dimmer, repeat the adjustment process for that side. Some vehicles have a slight inward angle on the low beam (so the right beam points slightly left and the left beam points slightly right), which is normal and improves visibility on curves.
Once both headlights are aimed correctly, turn them off and close your hood. Your adjustment is complete. If you are not confident in your measurements or the beams still look misaligned after adjustment, a tire shop or body shop can check your work with a professional headlight aiming machine, which is more precise than the wall method.
What to do if your headlights have automatic leveling
Newer cars with automatic leveling systems adjust the beam angle as the suspension compresses and extends. These systems use sensors to detect the car's pitch and tilt. If you have replaced a bulb or the system seems out of aim, check your owner's manual for a reset procedure—many systems reset by turning the ignition on and off in a specific sequence, or by pressing a button on the dashboard.
If the system does not reset and the beams still look misaligned, the sensors may be dirty or damaged. Clean the sensors (usually located near the wheels or suspension) with a soft cloth. If cleaning does not work, the system may need professional diagnosis, because automatic leveling cannot be adjusted manually the way traditional headlights can.
When to seek professional help
If your car was recently in an accident, the headlight housing, bracket, or reflector may be bent. Adjusting the screw will not fix a bent housing, and forcing the adjustment can damage the mechanism further. A body shop can assess whether the housing is salvageable or needs replacement.
If you have adjusted the screws fully in one direction and the beam still will not reach the correct aim point, the housing may be damaged or the adjustment mechanism may be broken. In this case, professional service is the safer choice. Some shops charge $20 to $50 to aim headlights as part of a larger service, or $75 to $150 if it is a standalone job.
Frequently Asked Questions
How often should I adjust my headlights?
Most drivers need to adjust headlights once or twice a year, or after any collision, suspension work, or bulb replacement. If you notice the beam pattern changing gradually, aim may have drifted due to vibration or settling. A quick wall check takes five minutes and tells you whether adjustment is needed.
Can I adjust headlights during the day?
No. You need darkness to see the beam pattern on the wall clearly. Adjust headlights at dusk, at night, or in a dark garage. Daylight will wash out the beam and make it impossible to see where it is actually pointing.
What if one headlight is much dimmer than the other?
Dimness usually means the bulb is old, the lens is cloudy, or the reflector is damaged—not an aim problem. Aim adjustment only changes where the light points, not how bright it is. If one beam is noticeably dimmer, replace the bulb first, then check aim. If brightness still does not match after bulb replacement, the headlight housing may need cleaning or replacement.
Do I need special tools to adjust headlights?
No. A screwdriver that fits the adjustment screws is all you need, plus a wall or garage door and a tape measure or marked reference point. Some adjustment screws use Phillips heads, others use flatheads or hex sockets—check your manual or look at the screw before you start so you have the right tool.
Will adjusting one headlight affect the other?
No. Each headlight has its own adjustment screws and adjusts independently. You can adjust one side without touching the other. However, both should be aimed to the same height and pattern for even visibility and to avoid blinding oncoming drivers on one side of the road.