Garage Door Won’t Close and the Light’s Blinking? Try This First.
Nine times out of ten this is a box on the floor, a spider web, or the sun. Here’s the checklist, in order — and we’re going to lose a service call by telling you.
You’re already running late.
You hit the button. The door starts down, makes it about two inches, changes its mind, and rolls right back up. Meanwhile the light on the opener is blinking at you like it’s trying to tell you something.
It is. It’s telling you the safety sensors aren’t happy.
Here’s the good news, and we’re going to lose a service call by telling you this: most of the time you can fix this yourself in about two minutes, for free. So before you call anyone — us included — work down this list.
First, the Thing That Explains Everything
Look at the bottom of your door tracks, both sides, about six inches off the floor. You’ll find two small plastic eyes facing each other across the opening.
Those are the safety sensors, and they’ve been required by law on every opener sold in the US since the early ’90s. They shoot an invisible beam across the doorway. If anything breaks that beam, the door refuses to close — because the alternative is a door closing on a kid, a dog, or the back of your car.
Notice the rule is one-directional. The door will always open. It only refuses to close. If your door opens fine and won’t go down, you’re almost certainly in the right article. If it won’t open either, that’s a different problem and the sensors aren’t it — very often that one is a broken spring.
On most LiftMaster and Chamberlain openers, the light blinking ten times is the specific code for “sensor beam broken.” Other brands click, beep, or just flash. Same meaning.
The Checklist, in Order
Work top to bottom. Stop when the door closes.
1. Look along the floor
The beam sits about six inches up, which is exactly the height of everything people leave in a garage. A trash bin edge. A bag of soil. A bike wheel. A broom that slid down the wall. A stack of Amazon boxes that’s two inches wider than you thought.
Clear a couple of feet on both sides of the opening and try again. This is the answer more often than the other five steps combined, and people skip it because it feels too obvious. Don’t skip it.
2. Look at the two little lights
Each sensor has a small LED. On Chamberlain-family openers (LiftMaster, Craftsman, Chamberlain) one shows green — that’s the sending side, and green means it has power. The other shows amber or yellow — that’s the receiving side, and it stays lit only while it can actually see the beam.
- Both steady? The sensors are talking. Your problem is probably somewhere else — skip down to the last section.
- Amber off or flickering? Something’s blocking or misaligning the beam. Keep going.
- Both dead? No power reaching them. That’s a wiring or opener problem, not a two-minute fix.
Genie and a few other brands use different colors, so check the sticker on the sensor rather than assuming. The principle holds regardless: steady light good, no light bad.
3. Wipe the lenses
Dry, soft cloth. Both eyes.
In Houston, this is a bigger deal than it sounds. Spiders love those little plastic housings, and a single web strung across the lens is enough to kill the beam. So is a season’s worth of dust off the driveway. Takes ten seconds and fixes a genuinely surprising number of these.
4. Check whether the sun is in its eyes
This one’s underrated and very Texas.
If your garage faces west, late afternoon sun can shine directly into the receiving sensor and wash out the beam completely. The sensor isn’t broken. It’s dazzled.
The tell: the door misbehaves at the same time of day, and works fine otherwise. If you’ve been thinking “it’s only weird in the evenings” — that’s your answer. Try it after dark to confirm. The permanent fix is a small shield or a shade over that sensor, or rotating it slightly out of the sun’s path.
5. Straighten the sensor
The brackets are thin metal and they bend if anything so much as leans on them. A bike, a trash can, a kid’s scooter, someone backing in a little too enthusiastically.
Loosen the wing nut, move the sensor by hand in small increments, and watch the amber light. When it goes solid and stays solid, tighten it back down. Small movements — you’re aiming a beam across a 16-foot gap, so a millimeter at the sensor is a lot at the far side.
6. Follow the wires
Two thin wires run from each sensor up the track and along the ceiling to the opener. Look for anything obviously wrong: a staple driven through the insulation, a section chewed by a rodent, a wire pulled loose, a green crusty connection where humidity got into it.
If you find damage, that’s where DIY ends for most people. It’s fixable, but it’s fiddly and it’s live low-voltage wiring into the opener’s board.
If You Need the Door Closed Tonight
There’s an override. You can hold the wall button — the one mounted inside the garage, not the remote — pressed down continuously, and the door will close in constant-pressure mode, ignoring the sensors.
Three rules if you use it:
- Stand where you can see the entire doorway the whole way down.
- Never with kids or pets anywhere near the garage.
- It is a get-through-the-night move, not a fix. The sensors are still broken tomorrow.
When It’s Actually Worth Calling
Some of these genuinely aren’t sensor problems, and knowing which is which saves you a service call:
- Both sensor lights are dead. Power isn’t getting there. Wiring, or the opener’s logic board.
- You found damaged wire. Fixable, not fun.
- Lights are steady and the door still reverses immediately. Not the sensors. Usually the close-force setting or the down travel limit.
- The door touches the floor and then bounces back up. Different problem entirely — that’s the travel limit set too low, telling the opener the floor is an obstruction. Common after someone’s “adjusted” it.
- Storm season aftermath. Houston lightning and surges kill sensors and opener boards with some regularity. If this started the morning after a bad storm, that’s probably related.
- You did all six steps and it still won’t close.
A sensor fault is one of the cheaper things that can go wrong with a garage door — and the estimate is free either way. There’s no service-call charge, so finding out what it is costs you nothing.
The Honest Summary
Nine times out of ten this is a box on the floor, a spider web, or the sun. Two minutes, no money, no appointment.
If it’s the tenth time, we’ll come out and sort it — and if we get there and it was just a box, we’ll tell you that too.
Blinking Light Questions
+Why is my garage door opener light blinking and the door won't close?
A blinking opener light with a door that opens fine but refuses to close is almost always the safety sensors — the two small eyes near the floor at the bottom of each track. They shoot an invisible beam across the opening, and if anything breaks that beam the opener refuses to close the door. On most LiftMaster and Chamberlain openers, ten blinks is the specific code for a broken sensor beam.
+Why does my garage door open but not close?
That one-directional behaviour is the signature of a safety-sensor fault. The sensors only ever prevent closing, never opening, because their whole job is to stop a door coming down on a person, a pet or a car. If your door will not open either, the sensors are not the problem and you are looking at something else — often a broken spring.
+How do I fix a blocked garage door sensor myself?
Work down six things in order. Clear anything sitting within a couple of feet of the opening — the beam sits about six inches off the floor, exactly the height of a bin, a bag of soil or a stack of boxes. Check both sensor LEDs. Wipe both lenses with a dry cloth. Consider whether afternoon sun is shining into the receiving eye. Straighten a bent sensor bracket by hand until the light goes solid. Then follow the wires for damage. Most of these are free and take about two minutes.
+What do the green and amber lights on garage door sensors mean?
On Chamberlain-family openers (LiftMaster, Craftsman, Chamberlain) the green LED is the sending side and simply means it has power; the amber or yellow LED is the receiving side and stays lit only while it can actually see the beam. Both steady means the sensors are talking to each other. Amber off or flickering means the beam is blocked or misaligned. Both dead means no power is reaching them. Other brands use different colours, so check the sticker on your own sensor rather than assuming.
+Can sunlight stop a garage door sensor working?
Yes, and around Houston it is more common than people expect. If your garage faces west, late-afternoon sun can shine straight into the receiving sensor and wash out the beam entirely. The sensor is not broken, it is dazzled. The giveaway is that the door misbehaves at the same time of day and works fine otherwise — try it after dark to confirm. The fix is a small shield over that sensor, or rotating it slightly out of the sun's path.
+How do I close my garage door when the sensors aren't working?
Hold the wall button inside the garage — not the remote — pressed down continuously, and the door will close in constant-pressure mode, ignoring the sensors. Stand where you can see the whole doorway the entire way down, never do it with children or pets near the garage, and treat it as a way to get through the night rather than a fix. What you should not do is permanently defeat the sensors by twisting the wires together or taping the two eyes face to face on a shelf. It works, and it removes the only thing standing between a closing door and whatever is underneath it.
+When should I stop trying and call someone?
Call when both sensor lights are dead, which means power is not reaching them; when you have found damaged or chewed wiring; when the lights are steady and the door still reverses, which is usually the close-force setting or the down travel limit rather than the sensors; when the door touches the floor and then bounces back up, which is the travel limit set too low; or when this started the morning after a bad storm, because surges take out sensors and opener boards. Also call if you have worked through all six steps and it still will not close.
+Do you charge to look at a garage door sensor problem?
The estimate is free and there is no service-call charge, so finding out what it is costs you nothing — and if we get there and it turns out to be a box on the floor, we will tell you that. Sensor faults are among the cheaper things that go wrong with a garage door.
Still Won’t Close?
Garage door acting up in Katy, Houston, Cypress or Sugar Land? Free estimate, no service-call charge, and a straight answer on how soon we can be there.