Fix a Garage Door That Won't Close

What is actually broken

Since 1993, openers shine an invisible infrared beam between two photo-eye sensors mounted near the floor on each side of the door. Break the beam — or convince the opener it's broken — and the door refuses to close or reverses mid-travel. The usual culprits are mundane: a sensor knocked out of alignment by a trash can, a lens filmed with dust and cobwebs, low sun shining straight into the receiving eye, or a nicked sensor wire along the track. The opener itself is rarely the problem.

The fix, step by step

1. 1 Read the sensor lights

   Find the two photo-eyes at the bottom of each track, about 6 inches off the floor. Each has a small LED: the sender is usually amber, the receiver green or red. Both lights should burn solid. A dark or flickering receiver means it's not seeing the beam — alignment, dirt, or a wiring fault. A blinking light on the opener itself is an error code; count the blinks and check the manual later if needed.

   Tip: The opener's wall button often blinks too when the sensors are unhappy — it resets once the beam is restored.

2. 2 Clean and clear the beam path

   Wipe both lenses with a soft dry cloth — spider webs and dust film the lenses surprisingly fast. Then clear anything crossing the beam path down at floor level: broom handles, bin lids overhanging the track, the recycling tub that crept an inch too far. Run the door and watch it travel fully.

   Tip: If the door only fails at certain times of day, suspect sun glare into the receiver lens — shade it with a short cardboard tube as a test, then buy a proper sun shield or swap the sensors side to side.

3. 3 Realign the photo-eyes

   If the receiver LED is dark or flickers, loosen its wing nut slightly and nudge the sensor until the light locks on solid — its partner across the door is your target. Tighten the nut while holding position, then do the same sanity check on the sender. Close the door fully and repeat twice; vibration from travel shakes marginal alignments loose.

   Tip: Watch the receiver LED while the door moves. If it flickers at the same point in travel every time, a door panel or track edge is swinging into the beam — shift that sensor slightly outward on its bracket.

4. 4 Check the sensor wires

   Still dead? Trace both thin wires from the sensors up to the opener head. Look for a staple driven through the wire (the classic), insulation chewed or rubbed bare at the track, and loose screw terminals at the opener. Repair a nick by stripping, twisting, and taping the two conductors — matching colors — or replace the run with bell wire. Re-test after each fix.

   Tip: Power-cycle the opener (unplug 30 seconds) after wiring work. Some units latch the sensor fault until rebooted.

5. 5 Test the safety reverse

   With the beam restored, lay a 2x4 flat on the floor in the door's path and close it: the door should touch and reverse within about two seconds. Wave a broom handle through the beam mid-close too — it should reverse instantly. Both tests passing means the safety system, not just the closing, actually works.

   Tip: Until it's fixed, you can close the door by holding the wall button down the entire travel (constant pressure overrides the sensor fault on most openers) — a one-time workaround, never a permanent habit.