Your garage door starts down, then stops and goes right back up. Or it will not close at all, and the opener light blinks at you. Nine times out of ten, the safety sensors near the floor are out of line or dirty. The good news: aligning garage door sensors is one of the few garage door fixes that is safe to do yourself. Here is how the sensors work, how to tell they are out of line, and how to line them up again.
How Garage Door Sensors Work
Every opener made since the early 1990s has two photo-eye safety sensors, one on each side of the door, a few inches above the floor. One sensor sends an invisible infrared beam across the opening, and the other one receives it. If anything breaks that beam while the door is closing, a child, a pet, a bike or a box, the opener stops and sends the door back up.
For this to work, the two sensors must point straight at each other. If one gets bumped by a car, a trash can, a lawn mower or a kid’s bike, the beam misses, and the opener acts as if something is in the way, even when nothing is.
Signs Your Sensors Are Out of Alignment
- The door goes down a little, then reverses and goes back up.
- The door closes only when you hold the wall button down the whole way.
- The opener light blinks, or the opener clicks, when you try to close the door.
- One sensor light is off or blinking, while the other is steady.
- The door works in the morning but not in the afternoon, when low sun shines into the garage.
On most LiftMaster and Chamberlain openers, the sending sensor has a steady amber or yellow light and the receiving sensor has a steady green light. If the green light is off or flickering, the sensors are not seeing each other. Genie and other brands use their own colors, often red and green, but the rule is the same: a steady light on both sides means they are lined up. Your opener manual lists the exact colors for your model.
How to Align Garage Door Sensors, Step by Step
- Clear the path. Move anything that sits between the two sensors: boxes, tools, recycling bins, leaves or snow.
- Clean both lenses. Wipe each lens with a soft, dry cloth. Dust, cobwebs and water spots are enough to block the beam. Don’t use spray cleaners or lubricant near the lens.
- Check the brackets. Look at the metal brackets that hold each sensor. If one is bent or loose, gently bend it back by hand so the sensor sits level and faces the other side.
- Loosen the wing nut. Each sensor is held by a wing nut or a small bolt. Loosen it on the sensor whose light is off or blinking, just enough to move the sensor by hand.
- Move it slowly. Turn the sensor a little at a time, up, down, left or right, until its light comes on and stays on without blinking. Some people run a string between the two sensors, or use a level, to help line them up.
- Tighten it. Hold the sensor in place and tighten the wing nut. Check that the light is still steady.
- Test the door. Close the door with the remote. While it is coming down, wave a broom handle or a box through the beam. The door should stop and go back up. If it does, you are done.
Sunlight, Cobwebs and Other Sneaky Causes
Low sun. When the sun sits low in the morning or late afternoon, it can shine straight into the receiving sensor and drown out the beam. If your door only acts up at certain times of day, try swapping the two sensors from side to side so the receiver faces away from the sun, or add a small sun shield over it. We can do this on a visit.
Spiders and insects. A single web across a lens can block the beam. Keep the area clean.
Wiring. The thin wires that run from the sensors to the opener can get stapled too tight, chewed, or cut by a shovel. If a sensor light will not come on at all, even after alignment, the wire or the sensor itself may be damaged.
Water and snow. Melting snow and road salt near the floor can corrode the sensors over the winter in Northeast Ohio. Wipe them off and keep the area around them clear.
Never Bypass the Sensors
It can be tempting to tape over the sensors, mount them up on the ceiling or tie the wires together to make the door close. Please don’t. The safety sensors are what keeps a closing door from coming down on a person or a pet, and the law requires them on every modern opener. If the sensors will not work, call us and we will fix or replace them.
When to Call Proactive Garage Door Repair
Call us at (440) 876-4444 if:
- The lights still blink, or one stays off, after you clean and align the sensors.
- A sensor, bracket or wire is damaged.
- The door reverses even with the sensors lined up, which can point to the opener’s force settings or a spring problem.
- The door is crooked, off its track, or heavy to lift. Don’t run the opener in that case.
Our garage door sensor repair service covers alignment, new sensors, wiring and remote problems. You always hear the price and approve it before we start any work. We offer same-day service on most calls, and we call you when we’re on the way.
Frequently Asked Questions
Why is one garage door sensor light blinking?
A blinking light usually means the sensors are not lined up, a lens is dirty, or something is in the beam. Clean the lenses, clear the path and align the sensors as shown above.
Can I fix my garage door sensors myself?
Often, yes. Cleaning and aligning the sensors is safe to do yourself. If a wire is damaged or a sensor has failed, we can replace it.
How high should garage door sensors be?
Most makers call for the sensors to sit about 4 to 6 inches above the floor, so the beam catches small children and pets. Check your opener manual for your model.
