You can adjust most headlights yourself with basic tools in about 15 minutes

Headlight aim — the direction your lights point — drifts out of alignment from normal driving, potholes, and minor collisions. When lights aim too high, they blind oncoming drivers. When they aim too low, you lose visibility on dark roads. Most vehicles let you adjust this yourself using two screws or bolts on the back of each headlight housing, accessible from inside the engine bay or wheel well. The adjustment takes a flat-head screwdriver or Phillips screwdriver, a level surface, and a wall or garage door to aim against.

You do not need a professional alignment machine for basic aim correction. A wall test takes five minutes and tells you whether your lights are close enough. If your headlights are severely misaligned — one pointing up and one pointing down, or both pointing sideways — or if you cannot locate the adjustment screws, a shop can do it with a headlight aiming machine, but this is rarely necessary for routine maintenance.

Key Takeaways

  • Most headlights have two adjustment screws: one for vertical aim (up and down) and one for horizontal aim (left and right), located on the back of the headlight housing.
  • A wall test on a level surface tells you whether your lights are aiming correctly before you start turning screws.
  • Vertical aim is the most common problem — lights that point too high or too low — and is usually the top screw.
  • Adjustments are small: a quarter-turn of the screw often moves the beam noticeably, so work slowly and test between turns.
  • If you cannot find adjustment screws or your lights are severely misaligned, a shop with a headlight aiming machine can do the job in under an hour.

Locate the adjustment screws on your headlight housing

Open your hood and look at the back of the headlight assembly — the plastic or metal housing that holds the bulb. You will see two screws or bolts sticking out, usually positioned at the top and side of the housing. The top screw controls vertical aim (up and down). The side screw controls horizontal aim (left and right). Some vehicles hide these screws behind a removable panel or require you to access them from inside the wheel well, so check your owner's manual if you cannot spot them when ready from the engine bay.

Write down which screw is which before you start. Take a photo of the housing with your phone so you can see the screw positions clearly. If your vehicle has sealed-beam headlights (older cars with round glass units), the adjustment screws are on the rim of the unit itself rather than on a plastic housing behind it. Modern vehicles with composite headlights almost always have screws accessible from the engine bay.

Set up a wall test to check current aim

Park on a level surface — a flat driveway or parking lot — about 25 feet from a wall, garage door, or light-colored building. Turn on your low-beam headlights and look at where the light hits the wall. The beam should form a clear pattern: the brightest part (the hot spot) should be slightly below the horizontal center line of the wall, and slightly to the right of center on the driver's side. This offset prevents blinding oncoming traffic while keeping the road ahead lit.

If both beams are pointing straight up, you will see light high on the wall and little light on the road ahead — this is the most common problem. If one beam is much higher or lower than the other, or if one points far to the left or right, you have found your problem. Mark the current beam position with tape or chalk on the wall so you can see the change as you adjust.

Adjust vertical aim with the top screw

Start with the vertical adjustment — the screw at the top of the headlight housing. Use a screwdriver that fits snugly in the screw head (usually a Phillips or flat-head, depending on your vehicle). Turn the screw slowly: clockwise typically raises the beam, counterclockwise lowers it, though some vehicles reverse this. Turn a quarter-turn, then go back to your wall and check the beam position. Do not turn more than a quarter-turn at a time, because small movements create large changes in beam direction.

Adjust until the hot spot of the beam is slightly below the horizontal center line of the wall. The light should reach the road surface clearly without shining into the eyes of oncoming drivers. Once the vertical aim looks correct, move to the horizontal adjustment.

Adjust horizontal aim with the side screw

The side screw controls left-and-right aim. Turn it slowly in quarter-turn increments, checking the wall between each turn. The beam should center slightly to the right of the wall's center on the driver's side headlight, and slightly to the left on the passenger side. This offset is intentional — it lights the road ahead while reducing glare for oncoming traffic.

If your vehicle has asymmetrical headlights (different beam patterns for driver and passenger sides), the passenger side may aim more toward center. Check your owner's manual or the headlight housing itself for any markings that show the intended aim pattern. Once both screws are set, turn off the lights and close the hood.

Test your adjustment on the road

Drive on a dark road with no oncoming traffic and watch how the road ahead is lit. The beam should illuminate the pavement clearly without creating a harsh cutoff line that makes it hard to see. If oncoming drivers flash their lights at you, your lights are still aiming too high — go back and lower them further. If you feel like you are not seeing the road well enough, raise them slightly.

Headlight aim can shift again after a few months of driving, especially if you hit a pothole or drive on rough roads. Check it every six months or after any impact to the front of your vehicle. If you adjust the screws and the beam does not move, the screw may be stripped or disconnected — this is a sign to have a shop look at it.

When to take your vehicle to a shop

If you cannot locate the adjustment screws, your vehicle may have headlights that require removal of the entire assembly to adjust — common on some newer models. If the screws turn but the beam does not move, the adjustment mechanism may be broken. If one headlight is severely misaligned compared to the other, or if you are uncomfortable working under the hood, a shop with a headlight aiming machine can do the job in 30 to 60 minutes.

Shops use a device that measures beam angle precisely and shows you the exact aim on a screen. This is more accurate than a wall test and is worth the cost if your lights are far off or if you have had front-end work done. Ask the shop to show you the before-and-after readings so you can see the correction.

Frequently Asked Questions

Which screw is which if I cannot tell them apart?

Turn the top screw a quarter-turn and watch the beam on the wall — if it moves up or down, that is your vertical screw. If it moves left or right, that is your horizontal screw. Turn it back to where it was and try the side screw. This takes two minutes and removes all guesswork.

Can I adjust headlights on a car with HID or LED lights?

Yes. HID and LED headlights use the same adjustment screws as halogen lights. The only difference is that the bulb itself cannot be adjusted — only the housing. The process is identical: locate the screws, test on a wall, and adjust in small increments.

What if my headlights keep drifting out of aim?

Repeated misalignment usually means the headlight housing is loose or damaged. Check that the bolts holding the entire assembly to the vehicle are tight. If tightening them does not help, the housing may be cracked or the adjustment mechanism may be worn — a shop can tell you whether the assembly needs replacement.

Do I need to adjust both headlights even if only one is misaligned?

Check both. If only one is off, adjust that one. If both are off in the same direction (both too high, for example), adjust both. Matching aim between the two lights matters more than hitting a perfect absolute angle — uneven lights are more noticeable to other drivers than lights that are both slightly high or low.

How often should I check my headlight aim?

Check every six months or after hitting a pothole, curb, or any impact to the front bumper or fender. Normal driving does not usually shift aim, but rough roads and collisions do. A quick wall test takes five minutes and tells you whether adjustment is needed.