If your garage door starts to close and then reverses back up — often with the opener light blinking — the photo-eye safety sensors are almost always the cause. These two small sensors near the floor shoot an invisible beam across the door opening; when the beam is broken or the two sensors aren’t pointed at each other, the opener refuses to close as a safety measure. Realigning them is a safe, tool-light job that takes about ten minutes and touches nothing under tension. Here’s how to get both lights glowing steady again.
What you'll need
- A soft, dry cloth
- A flashlight
- A screwdriver (usually a nut driver or Phillips)
- A level or string (optional)
Recommended parts & supplies
- Photo-eye safety sensor set — if a sensor is cracked, water-damaged, or won’t light at all
- Garage sensor mounting brackets — if a bent or broken bracket won’t hold alignment
- Low-voltage wire connectors — for a chewed or corroded sensor wire
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Step by step
- 1
Locate both sensors and read their lights
Find the two small sensors mounted on each track about six inches off the floor, facing each other across the opening. Each has an LED. Typically one is the “sending” unit (often steady amber) and one is “receiving” (often steady green) — and both should be solid and steady when aligned. If the receiving light is off or blinking, the beam isn’t connecting.
- 2
Clean the sensor lenses
Wipe each lens with a soft, dry cloth. Houston garages collect dust, spider webs, and grime, and even a filmy lens or a stray cobweb can break the beam. Sun glare late in the day can also blind a west-facing sensor — cupping your hand to shade it while testing rules that out. Cleaning alone fixes a surprising number of “won’t close” doors.
- 3
Clear anything blocking the beam
Check the floor line between the two sensors for anything interrupting it — a trash bin, a broom, a coiled hose, leaves blown in under the door. The beam sits low, so small objects are easy to miss. Clear the path completely.
- 4
Loosen and gently aim the misaligned sensor
If cleaning didn’t do it, loosen the wing nut or screw on the bracket of the sensor whose light is out, just enough to move it. Slowly tilt and swivel it toward the other sensor. Watch its LED as you go — when the beam connects, the light stops blinking and glows steady. Aim for both sensors at the same height and pointed straight at each other.
- 5
Check the height and level of both
Both sensors should sit at the same height off the floor. If a bracket has been knocked down over time, match them up — you can measure or run a string between them. Getting them level and even makes the alignment hold rather than drift. Once the light is steady, snug the fastener back down without nudging the aim.
- 6
Inspect the wiring if lights stay dark
If a sensor’s LED won’t light at all even when aimed correctly, follow its thin wire back toward the opener. Look for a break, a staple pinch, corrosion (common in humid garages), or rodent chew damage. A loose connection at the opener terminals is a frequent culprit. Reseating or splicing the wire can restore a “dead” sensor.
- 7
Test a full close cycle
With both lights steady, press the button and watch the door close fully without reversing. As a safety test, wave a broom through the beam mid-close — the door should immediately reverse, confirming the safety system works. If it closes cleanly and reverses on obstruction, you’re done.
When to call a pro
Sensor realignment is safe DIY. Call a professional if a sensor is cracked, water-damaged, or won’t light even with good aim and intact wiring — it may need replacing and re-pairing. Also call if the door still reverses after the sensors check out perfectly, since the opener’s force or travel settings, or a binding door, may be the real cause. One firm boundary applies here as everywhere on a garage door: if troubleshooting ever seems to lead toward the springs or cables — the parts under extreme tension above and beside the door — stop and call a pro. Never adjust or replace springs or cables yourself; the stored energy can cause serious injury. A sensor problem never requires touching them, so treat any such suggestion as a sign the diagnosis went wrong.
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How to Realign Your Garage Door Safety Sensors — FAQ
Why does my garage door open but not close?
What do the lights on my garage door sensors mean?
Can I bypass the garage door safety sensors?
Garage Door Repair & Installation services in Houston
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