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Garage Door Won't Close? Start With the Photo Eyes

·DoorBot Team

The classic call: door opens fine, but on close it reverses immediately — or won't move at all — and the opener light flashes. The remote "doesn't work" but the wall button does (if you hold it). That combination has one prime suspect: the photo eyes.

Why the door refuses to close

Since 1993, UL 325 has required openers to have a secondary entrapment protection system — almost always two infrared sensors about 6" off the floor. If the beam between them is broken, blocked, or the sensors can't see each other, the opener will not close the door. It opens freely because opening can't trap anyone.

The five-minute diagnosis

  1. Look at the LEDs. Both sensors should show solid lights (typically one green, one amber). A dark or flickering LED is your problem sensor.
  2. Clear the beam. Trash can, shovel handle, cobweb, kid's bike — anything in the path kills the close command.
  3. Clean the lenses. A film of dust scatters enough IR to matter. Soft cloth, no solvents.
  4. Check alignment. Sensors get kicked and brackets get bent. Loosen the wing nut, aim the sensor until its LED goes solid, retighten. Both LEDs solid = beam restored.
  5. Check for sun glare. Low sun shining directly into a receiver blinds it — symptoms that appear only at certain times of day are the giveaway. Shade the receiver or swap the sender/receiver sides.
  6. Wiggle the wires. Staple-pinched or hand-twisted sensor wires fail intermittently at the splice and at the opener terminals.

Sensor or logic board?

If the LEDs are solid, the beam is clear, and the door still won't close, count the opener's diagnostic flashes and run them through the Blink Code Decoder — the code distinguishes a sensor circuit fault from a board problem. Our flash-code guide covers how to read them by brand.

Do it right

The full alignment and wiring procedure — including the test block heights and what each brand's LED states mean — is in DoorBot's free Photo Eye Setup procedure. And after any sensor work, verify safety reversal per UL 325: the eyes are a life-safety device, not a convenience feature. Never bypass them to "fix" a closing problem.