Repair guide
Garage door won't close: start with the safety sensors
When a garage door starts down and then reverses, or the opener light blinks and nothing happens, the safety sensors are the most common cause. Most sensor problems take a few minutes to fix yourself.
Every automatic opener sold in the US since 1993 has a pair of safety sensors (photo eyes) near the floor on each side of the door. One sends an invisible beam to the other. If anything breaks that beam, the opener refuses to close the door or sends it back up. That safety feature is also the reason most "won't close" calls are an easy fix.
Quick fixes to try first
- Clear the doorway. Look for anything in the beam's path: a trash can, a broom, a box, a garden hose, even tall weeds or a spider web.
- Wipe both lenses with a soft cloth. Dust, cobwebs and water spots are enough to block the beam.
- Check the lights on the sensors. On most openers both sensors have a small LED. Solid lights on both usually mean they're lined up. If one is off or blinking, it can't see the other one.
- Realign the sensor. Sensors get bumped by bikes, bins and cars. Loosen the wing nut, aim the sensor straight at the other one until its light goes solid, then tighten it again.
- Check for low sun. Direct sunlight shining into the receiving sensor in the morning or late afternoon can blind it. If the door only misbehaves at certain times of day, that's the likely cause.
- Check the wires. Follow the thin wires from each sensor up to the opener. Look for staples through the wire, chewed spots or loose connections at the opener terminals.
If the sensors are fine
- The door reverses after touching the floor. The close limit or force setting may be off, so the opener thinks the floor is an obstruction. Adjusting these is in your opener's manual, but small changes matter; if you're unsure, have it set and tested.
- The door reverses partway down. Something is binding: a bent track, a damaged roller, or a hinge that's cracked. The opener feels the resistance and reverses. See garage door off track.
- The door is heavy or uneven. A broken spring or a loose cable makes the opener work too hard.
- The remote does nothing but the wall button works. That's a remote or lock-mode issue. See opener not working.
- You hold the wall button and it closes. That confirms a sensor problem: most openers let you override the sensors by holding the button down the whole way. Use it to secure the house, then fix the sensors.
How to test that your door reverses safely
Once a month, lay a 2x4 flat on the floor under the middle of the door and close it. The door should reverse as soon as it touches the board. Then wave something through the sensor beam while the door is closing; it should reverse. If either test fails, stop using the opener until it's adjusted.
Questions
Why does my garage door go down and then back up?
Most often the safety sensors can't see each other because they're blocked, dirty, or knocked out of alignment. Less often the close force or travel limit is set wrong, or something is binding in the track.
Why is the light on my garage door opener blinking?
On many openers a blinking light (often 10 blinks on LiftMaster and Chamberlain units) means a sensor problem. Check the sensor lights, clean the lenses and realign them.
How high should garage door sensors be?
The safety standard calls for the beam to be no higher than 6 inches above the floor, so it can detect a small child or pet.
Can I close my garage door if the sensors are broken?
On most openers you can hold the wall button down until the door is fully closed. Watch the door the whole time, and get the sensors fixed as soon as you can.