A blinking light on a garage door safety sensor means the two eyes cannot see each other, so the opener will not close. Safety: keep people out from under the door and never bypass the eyes. Lights: on LiftMaster and Chamberlain a blinking green, on Genie a flashing light. Beam: clear the path and wipe both lenses. Sun: low sun in the receiving eye. Wire: staples or chew marks.
Likely causes
- A sensor bumped out of line by a trash bin, a bike or a bumper
- Something in the beam, or a dirty lens or cobweb on the eye
- Low morning or afternoon sun shining into the receiving eye
- A sensor wire that is cut, chewed, stapled or loose at the opener
- A loose or bent bracket that lets the eye droop
What you are seeing
The door starts down, stops and goes back up, or will not close from the remote at all. One of the small sensors near the floor on each side of the door has a light that is blinking, flickering or off. The opener's own lights may flash too; on Chamberlain-made openers, ten flashes points back to these sensors.
These are the safety sensors, also called photo eyes. Openers sold in the United States since 1993 must have an entrapment-protection system, and on almost every one it is this pair of sensors, mounted about six inches off the floor. When the beam between them is broken, the door will not close. That is the system doing its job.
What the sensor lights mean, by brand
One eye sends an invisible beam and the other receives it. The colors depend on the opener family, and both makers publish what the patterns mean.
| What you see | What it means |
|---|---|
| LiftMaster or Chamberlain: amber on the sending eye, green on the receiving eye, both steady | Aligned and working |
| LiftMaster or Chamberlain: green blinking | Out of line, or something in the beam |
| LiftMaster or Chamberlain: amber on, green off | Wiring fault at the receiving eye |
| LiftMaster or Chamberlain: both off | No signal: a disconnected, shorted or broken wire, or a failed eye |
| Genie: red on the sending eye, green on the receiving eye, both steady | Normal |
| Genie: lights flashing | Beam broken or a fault: a dirty lens, something in the way or a loose wire |
Craftsman openers were made by Chamberlain and usually follow its colors; confirm in your manual.
Need your safety sensors fixed today?
Call or text with your address, single or double door, and what the door is doing. The price is firm before the truck leaves the yard.
What usually causes it
- Misalignment: a bin, a bike, a mower or a bumper knocks one eye a few degrees off.
- Blocked beam: anything in the path, plus dust, a cobweb or a spider on the lens.
- Sun glare: low sun shining straight into the receiving eye can blind it at certain times of day.
- Wiring: a staple through the wire, a rodent chew, or a loose connection at the opener. Both lights dark is the usual sign.
- A loose bracket that lets the eye droop out of line.
What you can safely check in two minutes
Keep people and pets out from under the door while you test it, and never tape, raise or bypass the eyes to get it closed.
- Read the lights. Find which eye is blinking or dark, and match it to the table above.
- Clear the beam. Move anything in the path and wipe both lenses with a soft dry cloth.
- Look at the aim. From the side, see whether one eye now points at the floor or the wall. Leave the bracket alone; realigning is a quick repair.
- Note the time. Failing only in the morning or late afternoon points to sun glare.
- Look along the wire for staples, chew marks or a pulled connection. Look, but do not splice.
Which repair fixes it
- Eyes out of line or a drooping bracket: realigned and the bracket reset so it cannot droop, through safety sensor repair.
- A cut, chewed or stapled wire: replaced and routed away from staples and shelving, the same repair.
- Sun in the receiving eye: the eyes swapped side to side, which is what Chamberlain recommends, or a sun shield where swapping is not enough.
- A failed eye: a new matched pair for the opener brand.
- Sensors fine, door still reverses: force, travel or the logic board; see will not close or reverses and opener repair.
We never bypass sensors or mount them up high to stop the blinking. They are what keeps the door from closing on a child or a pet.
When a repair stops making sense
Sensors are inexpensive parts and nearly always worth fixing. The exceptions sit behind them, in the opener.
- An opener with no sensors at all. It was made before the 1993 requirement, and it is time for a new opener, not a workaround.
- Sensors that keep failing because the logic board or its sensor terminals are failing. On an older unit, a new opener often makes more sense than a new board.
Replacement sensors are generally matched to the opener brand, so we confirm the make before we come. Our LiftMaster and Genie pages cover the two most common families, and opener replacement covers the case where the opener is the real problem.
Across San Diego
Sensor trouble has local patterns. Rancho Peñasquitos and Scripps Ranch have plenty of homes backing onto canyons, and garages near open land see more rodents. A chewed sensor wire, with both lights dark, is a typical result.
In Santee and the rest of East County, Santa Ana winds push dry leaves and dust into the garage, where they settle in the beam and film the lenses.
Anywhere in the county, a garage that faces east or west can catch low sun straight into a sensor at certain times of year. If your door refuses to close at the same hour every day, mention it when you book.
Sensor Light Blinking: common questions
Why is my garage door sensor light blinking?
A blinking light on the receiving sensor means it is not seeing the beam from the sending sensor. The usual causes are an eye knocked out of alignment, something in the beam, a dirty lens, sun shining into the receiver, or a damaged wire. Until the light goes steady, the opener will not close the door from a remote or keypad.
What does a blinking green light on a garage door sensor mean?
On LiftMaster and Chamberlain openers, the green light is on the receiving eye, and Chamberlain says a blinking green means the sensors are out of line or something is blocking the beam. Clear the path, wipe both lenses and look for an eye knocked off its aim. On Genie openers, flashing sensor lights mean the same thing: the beam is broken.
What does a yellow or amber light on a garage door sensor mean?
On LiftMaster and Chamberlain openers, the amber or yellow light is on the sending eye, and a steady amber means it has power. If the amber is on but the green light on the other eye is off, Chamberlain points to a wiring problem at the receiving eye. If the amber is off as well, the sensors are not getting power through their wire.
What does a red light on a garage door sensor mean?
On Genie openers, the red light is on the sending eye and the green light is on the receiving eye, and both steady means normal. Genie says a flashing red light means something is wrong: clean both lenses, clear anything in the beam and check for loose wires. The eyes should sit five to six inches off the floor, facing each other.
Why are my garage door sensors not lighting up?
When both sensor lights are dark, the eyes are not getting power. Chamberlain lists three causes: the sensors are not connected, a wire is shorted or broken, or a sensor has failed. Look along the wire for a staple, a chew mark or a loose connection at the opener, without splicing anything. The door will not close from a remote until the lights come back.
The FAQ page has more answers. Not sure which part failed? Send a photo and we will name it.
Where we see this
We cover all of San Diego County, same day in most cases. Some of the places we work:
Related guides
- Garage Door Won't Open or Close? A Safe Checklist: Garage door stuck? Safe checks in order: power, wall control lock, remote battery, sensor lights and release cord, plus which symptom needs which repair.
- How to Identify Your Garage Door Opener Brand and Model: Find your garage door opener's brand, model and remote type: where the label is, what the learn button color means, Genie tells and drive types.
- Garage Door Maintenance Checklist: Monthly, Twice a Year, Yearly: A garage door maintenance checklist: monthly safety tests, twice-yearly cleaning and lubrication, a yearly technician visit, and inland versus coastal.
Ready to get the door moving again?
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