Garage door opener

Troubleshooting Safety Sensors for Garage Doors

by Cecilia Harsch

In 1991, the Consumer Product Safety Commission began requiring all residential garage door opener manufactures to meet the entrapment protection provisions of the Underwriter’s Laboratories voluntary standards for garage door openers, making those standards mandatory. These standards require all openers to be equipped with invisible beam safety sensors that keep a garage door from closing when a child interrupts the beam. Fortunately, when damage occurs to the beam transmitter or receiver, your garage door opener will fail to operate. A few troubleshooting steps can help determine what caused the failure and what repair steps to take.

Locate your garage door opener sensors attached to the vertical door tracks on each side of the garage door, about 6 inches above the floor. Find the LEDs on the transmitter and receiver. Depending on which brand of opener you own, the transmitter will have either a red or amber LED, and the receiver will have a green LED regardless of the opener brand.

Remove any obstacles blocking the beam between the sensors. Tools, boxes, trash bags, dried leaves or toys can accidentally interrupt the beam and stop the garage door from closing.

Clean the transmitter and receiver eyes on the safety sensors with a damp cloth to ensure the transmitted beam reaches the receiver eye. Dirt and spider webs can block the eyes and interrupt the beam. The LEDs should glow steadily when the garage door is closed to indicate they are operating correctly; if both lights aren’t burning or they appear to be blinking, you should check the wiring for both sensors.

Check the wires connecting the sensors to the opener if your sensor lights aren’t working or appear to blink. Unplug the opener from the ceiling before reconnecting the wires to the sensors or opener if they have been pulled from their terminals. Tighten the terminals holding the wires if they appear loose. Replace the wires with a new strand of 20-2 bell wire if the wire appears frayed or broken. When you replace the wires, connect the new wires to the sensor and opener the same way the original wires are connected. Plug your opener back into the ceiling.

Adjust the receiver or transmitter sensor to line up the transmitted beam with the receiver eye if the green receiver LED isn’t burning or blinks. Some brands have wing nuts that hold the sensors to the sensor brackets, others have a large locknut around the transmitter or receiver eyes connecting them to the brackets, or the sensors slide over the sensor brackets. Loosen the nut on the receiver, if applicable, and move the sensor until the green light glows without blinking. Tighten the nut to hold the receiver in its new position. If your receiver slides over the bracket, bend the bracket forward or back until the green light glows. You may need to repeat these adjustments with the transmitter sensor if you can’t get the green light to glow after you adjust it.

Check for sprinkler heads that could spray the sensor if the garage door was open when you watered your yard. The water can cause the sensor to short circuit. Allow the sensor to dry before attempting to close the garage door with the opener.

Swap the safety sensor positions if the receiver receives direct sunlight at any time when you open the garage door. Unplug your garage door opener from the ceiling. Move the receiver to where the transmitter was installed originally and the transmitter to where the receiver’s original position. Don’t forget to swap the wire connections on the opener.

Replace your sensors with ones compatible with your opener if these troubleshooting steps fail to correct the issues with your garage door opener.

Items you will need

  • Cloth
  • Screwdriver
  • 20-2 bell wire

About the Author

Cecilia Harsch has been writing professionally since 2009. She writes mainly home improvement, health and travel articles for various online publications. She has several years of experience in the home-improvement industry, focusing on gardening, and a background in group exercise instruction. Harsch received her Certified Nurses Assistant license in 2004. She attended Tarrant County College and studied English composition.

Photo Credits

  • a remote control image by Ivan Hafizov from