Garage door won't close? Check the sensors first

If your garage door starts to close and then reverses, or won't close at all while the opener light blinks, the safety sensors are the first thing to check. They're the most common cause by far, and often you can fix them in a couple of minutes.

How the safety sensors work

Every opener made since the early 1990s has two small "photo-eye" sensors, one on each side of the door about six inches off the floor. They shoot an invisible beam between them. If anything breaks that beam, or if the two eyes aren't pointed at each other, the opener assumes something is in the way and refuses to close. That's a safety feature working as designed, even when it's a false alarm.

The usual culprits

• A sensor bumped out of alignment by a bike, a trash can, or a foot.
• A spider web, dust, or road salt film over the lens.
• Something actually in the beam: a cord, a leaf pile, a stray toy.
• Sun glare hitting one lens directly at certain times of day.
• A loose or damaged sensor wire.

How to realign the photo-eyes

Look at the little indicator lights on each sensor. Most brands light steady when the beam is aligned and blink or go dark when it isn't. Gently adjust the sensor that's blinking until both show a steady light. They're usually held by a wingnut or a bracket you can nudge by hand. Wipe each lens with a soft, dry cloth while you're there. Then test the door.

When it isn't the sensors

If both sensors show steady lights and the door still won't close, the problem is usually elsewhere: the opener's close-force or travel limits may be set wrong, a track may be obstructed, or the logic board may be failing. Those are opener adjustments better left to a tech, since a mis-set close-force can make the door unsafe. If you've cleaned and aligned the eyes and it still won't close, that's the point to call for an opener service.

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