Guide

Garage door sensor not working? Read the two little lights first

Updated August 20, 2026

The two small sensors near the floor of your garage door opening are the most blamed and least guilty parts on the whole door. They get kicked, bumped by trash cans, fogged with dust, and blinded by sunsets, and when the door won’t close everyone assumes they’ve died. They almost never have. The sensors also come with their own diagnostic display, which nearly nobody reads: one LED on each unit.

Before touching anything, look at both lights. Most brands put an amber or orange light on the sending unit and a green one on the receiving unit.

Both lights on and steady. The pair is aligned, powered, and seeing each other. If the door still won’t close, your problem is not the sensors, and you can skip to the last section.

The green (receiving) light off or flickering. The receiver isn’t getting the beam. Something is in the way, a lens is dirty, or one unit has been nudged out of aim. This is the common case and the fixable-today case.

Both lights dark. No power. The sensors run on low-voltage wire from the opener head, so look for a staple through the wire, a chewed section, or a loose connection at the opener terminals. Wire problems account for a surprising share of “dead” sensors, especially after shelving projects or a new freezer got shoved against the wall where the wire runs.

The five-minute fixes, in order

1. Clear the beam path. A rake handle, a bag of water softener salt, a bumper two inches further in than usual. Look low; the beam runs about six inches off the floor.
2. Wipe both lenses with a soft dry cloth. A season of dust or one cobweb is plenty to break the link.
3. Check the aim. Each sensor sits in a wing bracket that bends easily. Loosen the wingnut, point the units at each other until the green light goes steady, retighten. Steady light means you got it.
4. Follow the wire. From each sensor up to the opener head: staples, pinches, breaks. Low-voltage wire is cheap to splice or replace.
5. Test with the wall button. Sensors only supervise remote closing on most units. If the door closes while you hold the wall button down but refuses from the remote, that’s the sensor circuit confirming it’s the problem.

The sunset problem

Central Nebraska adds a failure mode the manuals barely mention: a flat horizon. A west-facing garage catches low direct sun straight into the receiving sensor in the evening, and the flooded receiver can’t distinguish the sender’s infrared beam. The door refuses to close from the remote at 7pm and works fine an hour later, and the pattern repeats on clear evenings for a few weeks each season. Fixes are unglamorous and effective: a cardboard or purpose-made sun shield around the receiving eye, or swapping the sender and receiver so the receiver faces east. If your “broken” sensor keeps office hours, this is it.

When it really isn’t the sensors

Steady lights but the door still reverses points elsewhere: the opener’s force or travel limits, or a mechanical bind in the door itself. The won’t-close guide walks that fork. And sensors that check out fine but drop the link when the door vibrates past suggest a failing logic board or a wire break that only opens intermittently

• at that point it’s an opener service call, and worth making, because a safety circuit that fails unpredictably is the one part of this system we don’t recommend living with.

Two lights, steady, aimed at each other. That’s the whole spec. Check it before you buy anything.