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

The fast answer

If your garage door starts closing, reverses immediately, and the opener light flashes — 7 times out of 10 you have a photo-eye issue. Good news: it's almost always a free, 5-minute fix.

What photo eyes do and where they are

Photo eyes (also called "safety sensors" or "photocells") are the two small units mounted about 6 inches off the floor on either side of your garage door opening. One sends an invisible infrared beam, the other receives it. If anything breaks that beam while the door is closing — a person, a pet, a bicycle — the opener refuses to close and reverses to protect whoever's in the way.

UL 325 (the industry safety standard) has required them on every residential opener sold since 1993. If your door is that old and has no photo eyes, the opener is not code-compliant and should be replaced.

The 3 things that go wrong with photo eyes

1. Dirty lenses

A cobweb, dust, or a smudge on either lens can break the beam just enough to trigger the safety. The lenses are small (about the size of a dime) and get overlooked in most home cleaning.

Fix: Wipe each lens with a dry, lint-free cloth. No cleaners, no water. Then press the wall button and watch the door close.

2. Misalignment

The two eyes must point exactly at each other. A bumped bracket, a kicked broom handle, or a kid's soccer ball can knock one out of alignment by a degree — enough to break the beam.

Fix: On almost every residential system, the receiver eye has a steady LED when aligned and flashing (or off) when misaligned. Find the flashing one. Loosen its wing nut with your fingers, tilt it gently toward the other eye, and watch the LED. The moment it goes steady, tighten the wing nut. Test.

3. Unplugged or broken wire

Photo eyes run on thin low-voltage wires from the opener head. Mice can chew them, staples can pierce them during garage finishing, or they can simply come loose at the opener.

Fix: Check the connections at the opener (small terminal block, usually on the back or underside). Check the wire runs. If a wire is obviously damaged, splice in a replacement length or run new 22-gauge wire.

How to tell photo eyes are the problem (by opener brand)

Most openers show a specific blink pattern on the opener light or LED:

• LiftMaster / Chamberlain: 10 flashes of the opener light
• Genie: 2 blinks on the diagnostic LED
• Craftsman (older): opener light stays on full-brightness or flashes with no rhythm

When it's NOT photo eyes

If you've cleaned and aligned both eyes, both LEDs are solid, and the door still reverses while closing — it's probably one of these:

• Close-force limit set too sensitive. Bump it up a quarter turn.
• Down-limit switch set too low — door hits floor, opener thinks it's an obstruction.
• Worn rollers near the bottom of the track creating resistance the opener reads as blockage.

See our full reversal-diagnosis guide for the other possibilities.

When to call us

If you've done the photo-eye and force-limit checks and the door still reverses, or if the photo-eye wiring is obviously damaged, it's time for a service call. Most of these fixes run $85–$165 complete. Book a diagnostic.

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