June 1, 2016

How to replace a garage door opener safety sensor

By Lyle Weischwill
How to replace a garage door opener safety sensor

This DIY repair guide explains how to replace a safety sensor on a garage door opener. The garage door opener has two sensors that prevent the garage door from closing on a person or object: one that sends an infrared beam and one that receives the beam. If an object or person is in the way of the beam, the closing door reverses direction. If a safety sensor stops working, the remote control won't work and the motor unit lights blink when you press the remote.

Our garage door opener safety sensor troubleshooting video can help you confirm a problem with the safety sensor. If you determine the safety sensors have failed, replace the sensors using the manufacturer-approved replacement part.

Follow the steps in this repair guide and video to replace safety sensors in Craftsman, Chamberlain, LiftMaster and Genie garage door openers.

Quick links
Tools required
Pliers
Wire cutters
Blue wire nuts (if crimp wire nuts aren't included)
Safety glasses
Work gloves
Step ladder
Repair difficulty
Time required
15 minutes or less
Repair difficulty
Time required
15 minutes or less
Replacing the safety sensors on a garage door opener

This video explains how to replace the safety sensors on a garage door opener.

Instructions

  1. 01.

    Disconnect the power

    Use a step ladder to access the garage door opener’s power cord and motor unit. Unplug the garage door opener.

    Unplug the garage door opener.

    Unplug the garage door opener.

  2. 02.

    Remove the sensors

    Remove the wing nut from the safety sensor.

    Pull the sensor from the bracket.

    Cut the wires about an inch from the safety sensor, leaving enough slack in the control wire to connect the new sensor.

    Repeat the process for the other safety sensor.

    Remove the wing nut from the safety sensor.

    Remove the wing nut from the safety sensor.

  3. 03.

    Connect the new safety sensor wires

    Separate the control wires on the new sensor.

    Connect the black-striped control wire to the black-striped safety sensor wire using the crimp wire nut.

    Connect the solid white wires the same way.

    Repeat the process for the other safety sensor.

    Tip: If you're not using the crimp wire nuts that come with the new safety sensors, strip 1/2-inch of insulation from each wire and connect the wires using wire nuts.
    Connect the safety sensor wires.

    Connect the safety sensor wires.

  4. 04.

    Install the new safety sensors

    Slide the safety sensor into its bracket and secure it with the wire nut.

    Repeat the process for the other safety sensor.

    Install the new safety sensors.

    Install the new safety sensors.

  5. 05.

    Reconnect electrical power

    Plug in the garage door opener.

  6. 06.

    Line up the safety sensors

    Align the safety sensors so the green indicator light on the receiving sensor glows steadily.

  7. 07.

    Test the safety sensor

    Open the garage door.

    Place a box or similar object between the safety sensors to block the sensing beam.

    Attempt to close the garage door using a remote.

    The door should stay open and the motor unit lights should blink.

    If the garage door opener closes the door with the safety sensors blocked, replace the logic board.

    Test the safety sensor.

    Test the safety sensor.

Warning: Undertaking repairs to appliances can be hazardous. Use the proper tools and safety equipment noted in the guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs should only be performed by a qualified technician.

Symptoms common to all garage door openers

Choose a symptom to see related garage door opener repairs.

Main causes: garage door locked, damaged garage door tracks, up-force setting needs adjustment, RPM sensor failure, bad drive motor
Things to do: check garage door travel, tighten brackets and fasteners, test safety sensors, check travel limits and force limits
Main causes: radio interference, weak remote batteries, sunlight interference with safety sensor beams, safety sensors need adjustment
Main causes: loose fasteners, broken brackets, need preventive maintenance, worn drive gears, loose or worn belt, loose chain
Main causes: neighbor's remote programmed at the same time as yours, faulty wall control wiring, bad wall control unit
Main causes: faulty logic control board, bad RPM sensor, broken gears in the drive system, bad drive motor
Main causes: garage door opener misaligned, travel limits need adjustment, bad travel limit switches, faulty logic control board
Main causes: safety sensor beams blocked, safety sensors not aligned, downforce setting needs adjustment, damaged garage door tracks

Repair guides common to all garage door openers

These step-by-step repair guides will help you safely fix what’s broken on your garage door opener.

How to replace a garage door opener safety sensor

If your remotes don’t work and the lights on the motor unit blink when you press a remote, the safety sensors may have failed. This guide will help you replace them.

Repair difficulty
Time required
 15 minutes or less
How to replace a chain-drive garage door opener gear and sprocket assembly

Learn how to replace the gear and sprocket assembly on your garage door opener if the drive motor runs but the door won't move.

Repair difficulty
Time required
 60 minutes or less
How to replace a chain-drive garage door opener drive and worm gears

If your garage door won’t move, the drive and worm gears could be broken. This guide will help you replace the gears.

Repair difficulty
Time required
 60 minutes or less

Articles and videos common to all garage door openers

Use the advice and tips in these articles and videos to get the most out of your garage door opener.

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