Why and when to adjust your car lights

Your headlights and taillights drift out of aim over time — from bumps in the road, minor collisions, or straightforward the wear on mounting brackets. Headlights that point too high blind oncoming drivers; lights that point too low leave the road ahead dark. Taillights that sit crooked may not be visible to traffic behind you. Most cars need a headlight adjustment every year or two, and any impact to the front or rear bumper is a reason to check alignment right away.

You can adjust most headlights and taillights yourself with basic tools. The process takes 15 to 45 minutes depending on your car's design. Some vehicles — particularly luxury models with complex lighting systems — require a dealer or specialist, but the majority of sedans, trucks, and crossovers have adjustment screws you can reach from inside the engine bay or behind the taillight housing.

Key Takeaways

  • Headlight adjustment screws are located on the back of the headlight housing and are usually marked with H (horizontal) and V (vertical) labels.
  • You will need a flat wall or garage door, a level surface 25 feet away, and a screwdriver — Phillips or flathead depending on your car's design.
  • Aim high-beam headlights so the brightest spot lands slightly below the center line of the wall at 25 feet, which prevents blinding oncoming traffic.
  • Taillight adjustment is simpler and usually involves loosening a single bolt or clip, then rotating the housing until the light sits flush and level with the body.
  • If your car has automatic leveling headlights or LED modules, check your owner's manual before attempting adjustment, as some require dealer service.

Tools and setup you will need

Gather a screwdriver (Phillips or flathead — check your owner's manual for your car's type), a tape measure, masking tape, and a marker or tape. You will also need a level surface — your driveway or a parking lot — and a flat wall or garage door 25 feet away. If you do not have a wall, a large piece of plywood or cardboard propped upright works.

Park your car on level ground perpendicular to the wall, with the front bumper 25 feet away. Make sure the car is not tilted — check with a level if the ground slopes. Inflate your tires to the pressure listed on the driver's door jamb, because underinflated tires lower the front of the car and throw off your aim. Turn off the engine and let the car sit for a few minutes so the suspension settles.

Mark the center of each headlight on the wall with tape or marker. Use a tape measure to find the height of each light from the ground, then mark that height on the wall. Draw a horizontal line across the wall at that height — this is your reference line.

Adjusting headlights step by step

Open your hood and locate the back of the headlight housing. You will see two adjustment screws: one labeled H or marked horizontally (usually on the side), and one labeled V or marked vertically (usually on top or bottom). Some cars use a single screw with a cam that adjusts both directions. Consult your owner's manual if you cannot find them — the location varies widely by manufacturer.

Turn on your headlights and set them to low beam. Step back and look at where the light beam hits the wall. The brightest spot should land slightly below the center line you marked — roughly 2 inches below the horizontal line at 25 feet. This angle prevents your lights from blinding oncoming drivers while still lighting the road ahead.

Use the vertical adjustment screw to move the beam up or down. Turn it slowly — a quarter turn often moves the beam several inches on the wall. Check your progress after each adjustment. Once the vertical aim is correct, use the horizontal screw to center the beam left and right on the wall. The brightest spot should be directly below the center mark you made on the headlight.

Repeat the process for the second headlight. Both should be aimed identically. Turn off the headlights, close the hood, and test your work by driving on a dark road — the beam should feel balanced and not too high.

Adjusting taillights and brake lights

Taillight adjustment is simpler than headlights because you are aiming for alignment with the car body, not a specific point on a wall. Open your trunk or hatchback and locate the taillight housing. Look for a bolt or clip on the outer edge of the housing — this is the pivot point.

Loosen the bolt or clip slightly so the housing can rotate, but do not remove it completely. Have someone stand behind the car and look at how the light sits relative to the body line. The housing should be flush and level — not tilted inward, outward, up, or down. Rotate the housing until it aligns, then tighten the bolt or clip firmly.

Check that the light lens is clean and not cracked. A cloudy or damaged lens scatters light and makes the taillight less visible to traffic behind you, even if the aim is correct. If the lens is damaged, the entire housing usually needs replacement.

When to take your car to a professional

Some vehicles have automatic leveling headlights that adjust themselves based on the car's pitch and load. These systems use sensors and motors, and manual adjustment will not work — the system will override your changes. Check your owner's manual for the phrase "automatic leveling" or "adaptive headlights." If your car has this feature, take it to a dealer or specialist for alignment.

LED and HID (xenon) headlight modules are also more complex than traditional halogen bulbs. If your car has these, the adjustment screws may control the entire module rather than individual bulbs, and the process is the same — but if the module itself is damaged or misaligned, it usually requires replacement rather than adjustment.

If you adjusted the lights and they still feel misaligned while driving, or if you cannot locate the adjustment screws, a shop with a headlight aiming machine can do the job in 30 minutes. The cost is typically $50 to $100 per pair of headlights.

Checking your work and maintenance going forward

After adjustment, drive on a dark road at dusk or night and pay attention to how the beam feels. It should light the road 100 to 150 feet ahead without creating a harsh cutoff or dark spot in the center. If oncoming drivers flash their lights at you, your headlights are too high — adjust the vertical screw down a quarter turn and test again.

Inspect your headlight and taillight housings every six months for cracks, moisture inside the lens, or loose mounting brackets. Moisture inside a sealed housing means the seal has failed and the housing will eventually corrode. A loose bracket will cause the light to drift out of aim again within weeks.

If you hit a pothole, curb, or another vehicle, check your light alignment the same day. Even a minor impact can shift the mounting brackets enough to throw off your aim. Catching it early prevents you from driving with misaligned lights and potentially causing an accident.

Frequently Asked Questions

Can I adjust my headlights during the day?

Yes, but it is harder to see where the beam lands on the wall. If you must adjust during daylight, darken the wall area with a blanket or cardboard, or wait until dusk when the ambient light is lower. The beam will be more visible and your adjustment will be more accurate.

What if one headlight is much brighter than the other?

The bulb in the dimmer light may be older or failing. Replace both bulbs at the same time — even if only one is dim, the other is likely near the end of its life. After replacement, check the aim again, because a new bulb may sit slightly differently in the housing.

Do I need to adjust my lights after replacing a bulb?

Usually not, if the bulb is the same type and wattage. However, if you switched from halogen to LED or HID, the beam pattern changes and you may need to re-aim. Check your owner's manual to confirm the bulb type your car is designed for.

How often should I check my headlight aim?

Once a year is reasonable for most drivers. If you drive on rough roads, hit potholes frequently, or live in an area with harsh winters, check every six months. Any impact to the front bumper is a reason to check the same day.

What if my taillight is cracked but still lights up?

A cracked lens scatters light and makes the taillight much less visible to traffic behind you, even though it still produces light. Replace the housing or lens as soon as you can — a rear-end collision is more likely when your brake lights are dim or hard to see.