Garage Door Sensor Not Working: Simple Checks

A garage door that goes down a few inches and then goes back up, or an opener light that blinks and refuses to close the door, is often a sensor problem. The safety sensors are a pair of small units about a hand's width above the floor, one on each side of the door. They send a beam across the opening. If something blocks the beam, the door will not close.

Start with the obvious: is something in the way? A bag, a box, a bike wheel or a toolbox can break the beam. Move anything away from the sensor area and try again.

Next, check the lenses. Dust, cobwebs and spider nests collect on the small lens at the front of each unit. Wipe each one with a soft dry cloth. Many sensors have a small light. A steady light usually means the beam is connected, and a dark or blinking light can mean misalignment or a wiring problem. The opener's manual lists what the lights mean for your model.

Check alignment. Each sensor is held by a bracket and can get bumped by a bike, a broom or a vehicle. Look to see whether the two units face each other and are at the same height. Gently nudge a bracket back into place if it has been knocked, then see whether the lights return to steady.

Check the wires. Follow the thin wire from each sensor to the opener on the ceiling. Look for staples that have cut it, a wire that has been chewed or a connection that has come loose. Do not work on wiring if the opener is plugged in. Unplug it first, or stop and call.

Bright sun shining into a sensor lens in the afternoon can also interfere with it. If the problem only appears at certain times of the day, that may be the reason.

Please do not bypass or disable the sensors. They are there to stop the door from closing on a person, a pet or a vehicle. If the lenses are clean, the units are aligned and the wires look fine, but the door still reverses, call. Your call is connected to an independent local service provider. You can also read our Garage Door Opener Repair page for related checks.