How to Test & Troubleshoot Garage Door Opener Sensors

Any residential automatic garage door opener manufactured after 1993 will not travel downward without a functioning automatic safety reverse mechanism, which means your garage can be left vulnerable to theft and intruders if your opener sensors malfunction. It’s important to test your garage opener sensors to ensure they are in proper working order to catch any indication of trouble before your door is unusable. North Shore Commercial Door has handled garage door sensors for decades, and below we’ve listed how to test your sensors as well as possible problems and fixes in case of a malfunction.

Why Are Garage Door Opener Sensors Necessary?

Federal law requires that all residential automatic garage door openers manufactured after January 1, 1993, must be equipped with safety reverse sensors. This important safety feature is designed to protect your family and pets from accidental injury or death due to entrapment. It works by automatically reversing the direction of the closing garage door in the event that it makes contact with a person or object in its travel path.

How to Test Your Automatic Safety Reverse Sensors?

Testing your automatic safety reverse sensors is an easy task to perform once a month. It costs nothing, only takes a moment to complete, and helps to ensure the overall safety and health of your automatic garage door opener system. Follow these simple steps to test your garage door's automatic safety reverse sensors:

  1. Place an object (such as a brick) on the ground directly in the path of the door. 
  2. Activate the garage door opener to close the door on the object. 
  3. The door should automatically reverse when it makes contact with or "senses" the object in its path. 
  4. If the door does not automatically reverse when it makes contact with the object in its path, additional troubleshooting may be necessary.

How to Troubleshoot Your Garage Door Opener Sensor?

If you experience difficulty with any of the steps in the testing process, there could be a range of issues \with your sensor, and most are easy fixes! Malfunctioning sensors could be a result of a faulty power supply, sunlight interference, dirty lenses, faulty wiring, or misaligned sensors.

Faulty Power Supply 

A garage door opener’s sensors can run into issues if its power supply is not functioning properly. 

How to Fix a Faulty Power Supply 

Check that the power supply is in good condition to ensure the problem lies in the sensor itself. 

Sunlight Interference 

The lenses on a garage door sensor rely on an infrared beam to detect if there is an object in the door’s way, and direct sunlight can potentially interfere with the infrared beam. 

How to Fix Sunlight Interference

Check that your garage door opener sensors are not in direct sunlight, and if so, find a way to shield them from the sun. Effective remedies include placing small pieces of cardboard (such as from a toilet paper roll) around the sensor except for the sensor itself, purchasing a sun shield for your sensor, or moving the sensor to a better location.

Dirty Lenses 

The lenses on a garage door sensor can also malfunction if they become dirty from dust and other debris over time, which messes with the signal. 

How To Fix Dirty Lenses 

Homeowners can easily clean their sensor lenses by using a soft cloth to wipe the lenses gently. If any debris remains, a moist cloth can be used to gently remove the access dirt. 

Wiring Issues 

Wiring issues such as a disconnected wire, improper wire connection, poor wire connection, or a shorted wire could also cause the safety reverse mechanism to malfunction. If you suspect a wiring issue, inspect the wiring to determine if the safety reverse sensors are wired incorrectly or disconnected entirely. 

How to Fix Wiring Issues 

Wires are generally color-coded to matching terminals. Locate the white and gray terminals on the back of the operator. White wires should be connected to the white terminal while black and white wires should be connected to the gray terminals on ChamberlainLiftMasterSears, and Raynor brand openers. On Genie openers, the wires can be connected to any terminal as they do not have polarity.

If the wires appear to be connected properly, here is a simple way to test for a shorted wire:

  • Disconnect the sensors from the brackets. 
  • Detach the wires from the wire nuts or snip them approximately 12" from the sensors. 
  • Strip the wires on both ends and twist the matching colored wires together on each sensor to the motor of the garage door opener. 
  • Unfasten the wires from the operator terminals and reconnect them according to color to the matching terminals. 
  • Direct the sensors at each other - if the LED lights on both sensors light up, there is a problem with the wiring and the wires will need to be replaced. 
  • If the LEDs do NOT light up, replace the sensors. 
  • If the LEDs still do not light up after replacing the wires or sensors, replace the logic board

What To Do If Your Wires Need to be Replaced?

If your opener’s sensor wires are damaged, it is best to hire a professional electrician to replace them for you. Not doing so can put you at risk for electrocution or damage the sensors further. 

Misaligned Sensors 

To determine if the sensors are misaligned, observe the LED indicator lights on the sending and receiving sensors. If they are flashing and not solid, the safety beams are either misaligned or there is an obstruction in the beam’s path.

How to Fix Garage Door Opener Sensors 

You don’t need a professional to realign and fix your garage door opener’s sensor issues. For a DIY home improvement project, be sure you have the following tools:

  • Gloves 
  • Regular screwdriver 
  • String 
  • A beam level 

After gathering the above items, follow these steps to fix your garage door sensor alignment:

Shut Off the Power 

First, locate your breaker box and trip the fuse that powers your garage to stop the electrical current from powering your sensors for your protection. Manually powered sensors can be simply unplugged from an outlet.

Don’t forget to wear protective gloves when handling electric wires!

Loosen Screws on Garage Door Sensor Mounts 

Next, you'll need to adjust the position of your garage door sensors. Find the mounting brackets for each sensor. Then locate the screws along the sides of these bracket mounts and use a screwdriver to loosen them enough that the mounting bracket can jiggle up and down a bit.

Shift the Mounting Bracket 

Now that the screws are loosened, lower each garage door sensor by sliding it downwards, ensuring it reaches the lowest point possible without causing the mounting brackets to unscrew completely.

Attach the String 

With the sensors lowered as far as possible, tie a string to one sensor and its bracket. Ensure the sensor cannot move within the bracket, then bring the extra string to the opposite sensor and attach it to the sensor and its bracket. Position the tied string so that it runs across the sensor’s center.

Level Your String 

To level your string, take a level and hold it against the bottom of the string. Make sure the string runs level. If it doesn’t, adjust the sensors by sliding the brackets upward until the string is level. Then remove the level.

Fasten the Sensor’s Mounting Bracket Screws 

Now that your sensors are level, tighten the screws to secure the garage door safety sensors in their new position. In case your sensors slightly shifted while tightening the screws, be sure to use your level on the string one last time to confirm it is still level.

Turn the Power Back On 

Now that your garage door sensors are aligned, remove the string. Turn the breaker box to your garage back on (or plug in the electric cord for manually-powered sensors). Test your sensors and see if they work properly. If the malfunction was due to misalignment, they should be functioning. 

What To Do If Garage Opener Sensors Still Do Not Work 

If these troubleshooting methods still fail to fix your sensor, refer to your garage door sensor's owner's manual or book a service appointment with a garage door specialist. A specialist will assist you in evaluating the issue with your sensor as well as what repairs or replacement parts are required.

Need more information on garage door sensors? North Shore Commercial Door prides itself on quality customer service and providing the best and most complete product information to its customers. Our in-house experts will be glad to answer your questions. Get in touch with our support crew: