Garage door sensors are aligned when both photo eyes sit 4 to 6 inches off the floor, face each other squarely, and both LEDs glow steady. Most misalignments take 10 to 15 minutes to fix with a screwdriver and a rag. If it still reverses after that, the cause is usually wiring, afternoon sun, or a failed eye, not alignment.
Why a garage door reverses instead of closing
Every residential opener sold in the United States since 1993 has two photo eyes near the bottom of the tracks. One sends an invisible infrared beam, the other receives it. If the beam is broken or the receiver cannot see the sender, the opener refuses to close from the remote and reverses the door back up. On most LiftMaster and Chamberlain units the overhead light also flashes 10 times, which is the opener telling you the sensors are the problem. If your opener is a Chamberlain, see our Chamberlain garage door opener troubleshooting guide for the rest of the flash codes beyond the sensor fault.
That behavior is deliberate. The eyes exist so a door that weighs 130 to 250 pounds never closes on a child, a pet, or a car bumper. Never tape the eyes together or wire around them to “fix” a door that will not close. Fix the reason they are not talking to each other.
A 30-second check before you touch anything
- Look at the floor between the eyes. A trash can wheel, a bike tire, or a broom leaning inside the track will break the beam.
- Look at both LEDs. On LiftMaster and Chamberlain, the sending eye shows steady amber and the receiving eye shows steady green when aligned. A green light that is off or flickering means misalignment. On Genie Safe-T-Beam eyes, red is the source, green is the receiver, and a blinking green means the same thing.
- Wipe both lenses with a dry microfiber cloth. Las Vegas garages collect a film of caliche dust within weeks, and a monsoon storm in July or August can coat a lens in one afternoon.
- Look for spider webs across a lens; black widows like the low corner where the bracket meets the track.
If the green LED comes back steady, you are done.
Tools you need
A Phillips screwdriver or a 7/16 wrench (brackets use a wing nut or a hex nut), a torpedo level, a tape measure, a flashlight, and a rag. A helper who watches the LED while you move the bracket cuts the job in half.
Step by step: aligning the sensors
- Unplug the opener. Pull the cord from the ceiling outlet; plugging it back in later also resets the logic board.
- Measure both eyes. Measure from the concrete to the center of each lens. They should be within a quarter inch of the same height, typically 4 to 6 inches. If one bracket has slipped, loosen its wing nut and slide it to match.
- Check the brackets are tight to the track. A bracket that wiggles when you touch it will never hold alignment. Tighten the mounting screws into the track or the wall stud first.
- Square the eyes. Loosen the wing nut on the receiving eye (the green one) just enough that the eye pivots. Point it straight across at the sender. Sight down the top of the sensor housing like a rifle barrel.
- Watch the LED while you fine tune. Plug the opener back in. Rotate the receiving eye slowly up, down, left, and right until the green LED is bright and steady, then find the middle of the range where it stays steady and lock the wing nut there. Do not overtighten; the plastic housing cracks.
- Test. Close the door from the wall button and let it run fully. Then open it, place a roll of paper towels in the beam, and press close. The door should refuse to move or reverse within a second or two. Remove the roll and close it again.
Total time for a door that was simply bumped out of line is 10 to 15 minutes. If you are back here in three months, something is moving the bracket and the next section applies.
Las Vegas problems that alignment will not fix
Late afternoon sun on west-facing garages
This is the single most common sensor call we take in Summerlin, Spring Valley, and the west side of Henderson. Between roughly 4 pm and sunset, low sun pours straight into a west-facing garage and floods the receiving eye with infrared, so it cannot distinguish the sender’s beam. The door works fine at 9 am and refuses to close at 5 pm. Two fixes work: swap the eyes so the receiver (green) is on the side that gets shade, or slide a 3-inch length of black PVC or a rolled piece of cardboard over the receiver lens as a sun hood. Some newer sensors ship with a hood for exactly this reason.
Dust storms
The monsoon season, roughly July through September, pushes fine dust under the bottom seal and onto the lenses. If your door acts up the day after a storm, clean the lenses before you loosen anything. A worn bottom seal makes this worse; see our guide on sealing the garage against dust and pests.
Chewed or stapled wires
Sensor wire is thin bell wire run along the track and up to the motor head. Roof rats chew it, and the staples that tack it to drywall can pierce the insulation after years of 120 degree summers. Look for exposed copper, a staple through the wire, or a taped splice. A shorted wire kills the LED entirely, not just the alignment.
Bent brackets and moving slabs
A bracket clipped by a car tire or a trash can bends and will not hold position no matter how often you realign it. Replace it. On tract homes in North Las Vegas and Henderson built on expansive soil, slab movement in the wet season can also shift a bracket enough to lose the beam.
Heat-killed sensors
Photo eyes are electronics living 5 inches off a concrete floor in a garage that reaches 110 to 120 degrees for weeks each summer. Sensors 12 to 20 years old become intermittent: fine at dawn, failing by mid afternoon, fine again after dark. If the LED dims or flickers with nothing in the beam, the eye itself is failing. Sensors are replaced as a matched pair during a service call, priced by the job with a written quote first.
If the LED will not light at all
No LED on either eye means no power is reaching the sensors. At the motor head, confirm the two sensor wires are seated in the correct terminals (white and white with a black stripe, terminals 2 and 3 on LiftMaster), then check the wire run for damage. If the wiring is intact and the opener still shows a sensor fault, the logic board is the likely failure, and on an opener older than 15 years a new opener usually costs less than a board plus labor. Our garage door opener installation page covers what a replacement includes, new sensors among it.
One safe diagnostic: hold the wall button down continuously. Most openers close with the eyes bypassed only while the button is held. If the door closes that way, the fault is isolated to the sensor circuit. If it reverses even while you hold the button, the sensors are not the problem; it is a force or travel setting, or a binding door, which our post on adjusting garage door opener sensitivity covers.
Keeping the sensors aligned
- Wipe both lenses every 2 to 3 months and after every dust storm.
- Keep a 12-inch clear zone around each eye. Move the trash cans, the bikes, and the shop vac.
- Test the reverse function monthly with a 2×4 laid flat on the floor under the door. The door must reverse on contact.
- Have brackets, wiring, and eyes checked at an annual tune-up, which also catches the worn rollers and tired springs that actually break doors; see our guide to garage door component lifespans.
When to call Supreme Garage Doors
Call (702) 356-1697 if the door still reverses after 15 minutes of aligning, if either LED stays dark, if you find cut or chewed wire, or if the door drops hard or will not stay up when you pull the release cord. That last one is a spring or cable failure, not a sensor issue; our garage door spring repair page explains what is involved. Supreme Garage Doors answers 24/7, sends a technician the same day on most calls across Las Vegas, Henderson, and North Las Vegas, and gives a written quote before work starts. Sensor realignment is included in a standard garage door repair visit.
Frequently asked questions
How high off the floor should garage door sensors be?
Both photo eyes should be mounted 4 to 6 inches above the concrete, measured to the center of the lens, and within a quarter inch of each other in height. Lower than 4 inches and dust and debris block them; higher than 6 inches and a small child or pet could pass under the beam.
What do the lights on garage door sensors mean?
On LiftMaster and Chamberlain openers the sending eye shows a steady amber light and the receiving eye shows a steady green light when aligned. A green light that is off, dim, or flickering means the eyes are misaligned or dirty. On Genie openers the source LED is red and the receiver is green; a blinking green means the same alignment fault.
Why does my garage door only refuse to close in the afternoon?
Low western sun is flooding the receiving eye with infrared, which is common on west-facing garages in Las Vegas between about 4 pm and sunset. Swap the eyes so the receiver sits on the shaded side, or fit a short black tube or hood over the receiver lens. The door will work normally the rest of the day, which is the tell.
Can I bypass the garage door sensors?
Not permanently. Openers built since 1993 are designed to refuse remote closing without working sensors, and disabling them removes the only protection against the door closing on a person or a car. Holding the wall button down closes the door with the eyes bypassed as a one-time diagnostic, but the sensors should be repaired the same week.
How much does it cost to replace garage door sensors in Las Vegas?
A matched pair of replacement photo eyes is installed as part of a service call in the Las Vegas area, including wiring checks and alignment, and is priced by the job with a written quote before the work. If the opener is more than 15 years old and the logic board is also failing, replacing the whole opener is usually the better value than repairing the board.