Symptom check
One of the little eyes by the garage door is flashing
A photo eye blinks when its beam is not reaching the other eye, because the pair is out of line, a lens is dirty or wet, or sun is shining in. Realigning and cleaning fix most cases; a dark eye means a wiring repair.
Updated
Read both eyes before touching the opener
Find the two small sensors near the floor on either side of the door and note which light blinks, which holds steady and which is dark. Clear anything between them and dry both lenses. Never tape over, unplug or bypass the eyes to get the door shut, because they are what stops it closing on a child, a pet or a car.
What usually causes it, in order
The eye that blinks, and its color, tells you which of these you are looking at, so read the brand table further down too.
- Most common
The eyes are knocked out of line
What you notice: One light blinks or glows dim while the other holds steady, often after a bike, a bin or a broom bumped a bracket.
The repair: Realign the eyes and tighten the brackets, or replace a bent bracket so the pair stays aimed. Garage Door Safety Sensor Repair, from $125
- Common
A dirty, wet or blocked lens
What you notice: Cobwebs, mud splash, condensation or a stored item sits in the beam path at the bottom of the opening.
The repair: Clean and dry the lenses and clear the path; eyes that sit in constant splash can be moved a few inches. Garage Door Safety Sensor Repair, from $125
- Common
Sunlight shining into the receiving eye
What you notice: Blinking and a refused close arrive together while bright sun sits on the receiving lens, and both stop once the light moves off it.
The repair: Put the receiving eye on the side of the door the sun does not reach, or shade it, keeping both eyes low. Garage Door Safety Sensor Repair, from $125
- Less common
A damaged or loose sensor wire
What you notice: One or both lights are dark even though the opener has power, and the thin wire along the wall or track is stapled through, chewed or pulled loose.
The repair: Trace and repair the low-voltage run, replacing damaged sections and remaking loose connections at the opener head. Garage Door Safety Sensor Repair, from $125
- Less common
A sensor that has failed
What you notice: The lights stay dark or flicker with sound wiring and clean, aimed lenses, often on eyes that have sat in a damp corner for years.
The repair: Replace the pair with sensors made for your opener, then test that a closing door reverses. Garage Door Safety Sensor Repair, from $125
Safe checks before you call
Each check is done at floor level and needs nothing more than a dry cloth and your eyes.
- Before changing anything, note which eye blinks, which is steady, which is dark, and their colors.
- Clear the path between the eyes, including bins, mats, leaves and anything hanging into the opening.
- Dry and clean both lenses; condensation and road spray build up on them through the wet months.
- Push gently on each bracket to see whether it has bent or swung loose on the track.
- Follow the thin wire from each eye toward the opener as far as you can see it, looking for staples, chew marks or a pulled connector.
- Watch whether the blinking stops when a cloud covers the sun or the sun moves off the door.
What each sensor light means, brand by brand
For every brand in the table, steady lights mean the eyes are aimed and working, while a blinking or dark light means a fault, and the colors differ by maker.
The LiftMaster and Chamberlain rows come from Chamberlain support for its current safety sensors; older eyes and other brands can behave differently, so the opener manual has the final word.
| Brand | What you see | What it means |
|---|---|---|
| LiftMaster and Chamberlain | Amber steady on one eye, green steady on the other | Normal: the amber eye sends, the green eye receives |
| LiftMaster and Chamberlain | Green light blinking | Eyes out of line or something in the beam |
| LiftMaster and Chamberlain | Amber on, green dark | Wiring fault on the receiving eye |
| LiftMaster and Chamberlain | Both eyes dark | Wiring fault on the sending eye |
| Genie | Both lights steady | Normal operation |
| Genie | Red light flashing | A fault: clean the lenses, then check aim and wiring |
| Marantec | Red light blinking | Eyes out of alignment |
| Marantec | Both lights dark | Eyes have lost their connection to the opener |
Why the sensor blinks in bright sun
Sun aimed straight into the receiving eye can swamp its infrared beam, and Chamberlain notes the opener then behaves as if something is in the doorway.
Chamberlain's own fix is to swap the two eyes between the tracks, and it warns that a swap can shift the glare from morning to evening rather than end it; for that case it offers a sun shield for the receiving eye. If the blinking follows the sun, try the swap first, then the shield.
Do not raise the eyes to dodge the glare. Genie puts the lenses about 5 to 6 inches off the floor, facing each other, and an eye mounted higher can miss a small child or a pet lying in the opening.
Why the eyes are never taped, bypassed or mounted high
Photo eyes are how most residential openers meet the federal entrapment rule, which covers every unit manufactured for American sale from the first day of 1993.
The opener checks the eyes on every close and refuses a remote close when they fail. Some older LiftMaster and Chamberlain openers let you close by holding the wall button down, but Chamberlain says openers and boards made after February 3, 2022 no longer allow it. Either way, the fix is the eyes, not a workaround.
A sensor call usually ends with a bracket set back in line, a lens cleaned or a wire run replaced, then a full close onto a board lying on the slab to prove the door reverses.
Sensor light blinking: questions and answers
What does it mean when a garage door sensor light is blinking?
A blinking sensor light says the beam between the two eyes is broken, and remote or keypad closes are refused until it is restored. On LiftMaster and Chamberlain eyes, a blinking green light means misaligned or blocked. On Genie and Marantec eyes, a flashing red light signals the same kind of fault.
Why is one garage door sensor yellow and the other green?
On LiftMaster and Chamberlain eyes that is normal: the amber, or yellow, eye sends the infrared beam and the green eye receives it. Both glowing steady means the pair is aimed and working. Trouble shows as a blinking green light, or one or both lights going dark.
How do I realign a garage door sensor that keeps blinking?
Loosen the wing nut on the receiving eye, point its lens straight at the other eye, and tighten it once the light holds steady. Keep both eyes low, about 5 to 6 inches off the floor in Genie instructions, and run a full close to confirm. Straighten or replace a bent bracket first.
Can sunlight make my garage door sensor light blink?
Yes, sun shining straight into the receiving eye can drown out the beam, and Chamberlain lists it as a reason doors will not close. The sign is blinking that comes and goes with the sun. Putting the receiving eye on the side that stays out of the sun, or hooding it, usually ends it.
Why is my garage door sensor light off completely?
A dark sensor usually is not getting power through its wire. On LiftMaster and Chamberlain eyes, both lights off points to the sending eye wiring, and a dark green light beside a lit amber one points to the receiving eye wiring. Look for staples, chewed insulation or a loose connection at the opener.
Can I splice a chewed garage door sensor wire myself?
A clean cut in the thin low-voltage wire can be spliced with the opener unplugged, and the lights should return once the circuit is whole. Chewed wire is often damaged in several places along the wall or ceiling, though. If the lights stay dark after a splice, the fault is farther along the run or in the eye itself.
Where to go next
Nearby service areas
This call comes in from Five Corners, Kalama, Meadow Homes and the rest of our Washington service area.
Want a price before anyone drives over?
Call and describe what the door is doing, or text a photo of the door and the spring above it. You hear the likely repair and where its price starts, then decide.