How often should you test the garage door safety reverse?

Short answer

Test the garage door auto-reverse once a month. A garage door opener has safety features that stop and reverse the door when it hits something or when the beam between the sensors near the floor is broken, and both can fail silently. Laying a 2x4 flat on the floor under the door and closing it, then breaking the sensor beam with a wave as the door comes down, takes 5 minutes and costs nothing.

Why it matters

A garage door weighs more than most people can lift, and it comes down with enough force to crush whatever is under it. The opener's safety systems are what make that acceptable in a house with children and pets. The contact reverse feels resistance and sends the door back up. The photo-eye sensors, the little lenses facing each other a few inches off the floor, see anything crossing the beam and stop the door before it touches.

Both systems drift. The force setting on the opener creeps up as the door gets heavier with age and dirt, until the door pushes through what it should have reversed on. A sensor gets bumped out of line, its lens gets dirty, or its wire gets pinched, and the opener either refuses to close or, on some older units, closes without the sensor at all. The monthly test is the only way to know the door will stop for a child's bicycle, or a child.

When to do it more often

Monthly is the schedule, and there are no listed modifiers. The events that call for a test between are anything that touches the system: a new opener, a change to the opener's settings, work on the door, a bump to a sensor bracket, and a hard freeze that can stiffen the door and change how it moves. If the door has ever hit something without reversing, test it before the next use, and keep testing until a technician has fixed it.

What you need

A 2x4 board, or a roll of paper towels, to put under the door for the contact test

Steps at a glance

Lay the 2x4 flat on the floor in the door's path, roughly in the middle.
Press the button to close the door. When it touches the board, it should stop and go back up within a second or so.
Take the board away, press the button to close the door again, and as it comes down, wave a foot or a broom handle through the sensor beam.
The door should stop and reverse without touching anything.
Look at the sensors: each should show a steady light, and the lenses should be clean and facing each other squarely.
If either test fails, stop using the opener for closing until it's fixed, and close the door by hand instead.

You're done when the door reversed off the board and reversed when the beam was broken.

Signs it's overdue

The door doesn't reverse when it touches the board.
The sensor lights blink, or one is dark, which means they're out of line or a wire is damaged.
The door reverses for no reason on its way down, which is a sensor seeing something that isn't there, often sunlight or a dirty lens.

DIY or pro

The test is an easy job, and the fix for a sensor that's out of line is often easy too: loosen the bracket, nudge the sensor until its light goes steady, and tighten it again. A dirty lens wipes clean with a cloth. Those are the common problems, and the test finds them.

A door that fails the contact test needs its force setting adjusted, and on some openers that's a dial you can turn as the manual says. If turning it down a little doesn't fix the reverse, or if the door is heavy and out of balance, call a technician. A garage door company charges $100 to $200 to realign or replace the sensors and set the opener up properly. Don't disable or bypass a sensor to make the door close, however tempting on a cold night.

Safety

Structural: the point of this test is that the door is heavy enough to hurt someone. Stand clear while it moves, keep children and pets out of the garage during the test, and don't reach under a moving door to grab the board. If a test fails, close the door by hand until the opener is fixed.

FAQ

How do you test garage door sensors?

Start the door closing and wave something through the beam between the sensors near the floor. The door should stop and reverse at once.

Why won't my garage door close all the way?

Usually a sensor problem: the sensors are out of line, a lens is dirty, or sunlight is hitting one. A blinking sensor light points to it. Realign and clean them.

Why does my garage door reverse on its own?

The sensors are seeing something, or the opener's force setting is too low for a door that's gotten stiff. Check the sensors first, then have the door's balance looked at.

Is it safe to bypass the garage door sensors?

No. The sensors are what keep the door from closing on a person or a pet. Fix them rather than working around them.