Garage Door Sensors: Everything You Need To Know

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You may not give them much thought, but those sensors at the bottom of your garage door impact how your garage door opener works.

This article will briefly describe how garage door sensors work, the different types, and why you need them. Finally, we’ll review our universal garage door sensor recommendations if you need to replace yours.

How Do Garage Door Sensors Work?

Garage door opener sensors are also called photoelectric safety sensors. They ensure that your garage door stops closing or opening when it recognizes that there’s something in its way.

It’s a great safety feature. It can seem complicated at first glance if you have never looked into how this technology works.  

Garage door sensors shoot an infrared light beam across your garage entrance to the sensor on the other side. The sensors usually are about 4 inches above the ground.

This system allows them to detect obstructions like your car or a kid on a bike. The door will open or close as long as the beam isn’t interrupted.

The infrared beam from the garage door opener sensors can’t be seen by human eyes.

So don’t look for red laser lines like in the movies – they won’t be there.

Types of Garage Door Opener Sensors

There are three primary types of photoelectric safety sensors on the market.

While they basically all do the same thing, understanding their differences helps you pick the right one for your garage.  

Through-beam Safety Sensors

These are the most common garage door opener sensors you’ll find. They work thanks to two devices located oppositely from each other. The first unit (emitter) creates the light beam, which is then received by the second unit (receiver).

Any time an object or person crosses the light beam, the connection between the two units is broken. The sensors then send a stop signal to the electric motor of your garage door.

Retro-reflective Safety Sensors 

These garage door sensors take the idea of an emitter and receiver and put them both in the same unit to save space.

In this case, one part of the sensor creates a beam of light that crosses the garage door. A retroreflector on the other side of the garage door reflects the light ray directly to the receiver element.

The beam loses some strength when something is in the way of the sensor and the retroreflector, or it is partially reflected and hits the sensor at different angles and strengths.

Why Do You Need Garage Door Sensors?

The short answer is that it’s the law.

In 1993, the U.S. Federal Law UL 325 made it mandatory for manufacturers to include sensors that interrupt opening and closing your garage door. That law states they need to be able to reverse the door’s motion within 2 seconds.

This protects users from injuries while making garage doors more convenient and efficient.  

Besides being the law, installing safety sensors has some other benefits as well:

  • Protecting your car or other vehicles from damage and scratches
  • Preventing you and your family from entrapment or severe injuries, especially if your garage has a steel door
  • Small children and pets running in and out of the house can inadvertently collide with a closing or opening door. Garage door sensors lower the risk of harm.

Although it’s possible, we do not recommend bypassing your garage door sensors.

Common Issues with Garage Door Sensors

Just like the yearly maintenance you need to do for your garage door, there are some things you can do to help keep your sensors working correctly, too. Usually, it’s just some small cleaning and adjustments because the sensors are durable.

If the garage door sensors haven’t experienced a significant failure, you should be able to quickly troubleshoot them. It’s often possible to get them working in only a few minutes. 

Here are the most common issues you might have to solve during the life of your safety sensors.

Dirt & Dust 

Since they are located just off the ground, sensors can quickly become dirty after several months of continuous use. Dust and debris can create a layer on the surface of the emitting or receiving sensor, producing a barrier for the light beam. 

This obstruction can result in your garage not opening or closing correctly. In this case, use paper towels and an all-purpose cleaner to get the sensors to work.

It’s good to take a lint-free cloth and wipe off the emitter lenses or reflector at least once per year. You may need to do this more often if you have a lot of dust in your garage.


Whether your sensor system boasts two or only a sensor and a mirror, they must be perfectly aligned.

Unfortunately, it’s very easy to knock them out of line by mistake, especially if using your garage as a storage area or workshop. 

To adjust the modules, use the following steps:

  1. Loosening the screws that keep the sensors in place without removing them from their original position. 
  2. Shift both sensors until the power indicator lights, which can be either green or red, are on and the same color.
  3. Once the indicators are on, the circuit is aligned, and you can secure the devices.


As I mentioned, anything that breaks the beam will stop your door from opening or closing correctly.  

I’m betting it’s easy to see if a child’s tricycle is in the way, but other obstructions might not be as obvious.

For example, leaves, rocks, or other debris can quickly pile up in front of the sensor. Try to stop leaves from blowing into your garage and clean them out before trying to activate the door.

The Best Universal Garage Door Sensors

Are garage door sensors universal?

Sometimes, but not typically.

Most garage door sensors don’t immediately tell you what brand of garage door opener they work with.

Often, the only way to tell whether your garage door sensor is universal is to check the manual or contact the manufacturer.

However, if you do decide to replace your old sensors, here are a few that I recommend:

Digi-Code-Universal Sensors CR2149

The CR2149 universal sensor works with every major garage door brand. The installation is quick, and it comes with mounting brackets and screws for you to fasten the sensors to the door. If you need an affordable and effective solution, the CR2149 is a great inexpensive option. 

It’s worth noting that some users experience light sensitivity issues with this brand, which can make it less reliable in brighter garages.  

Digi-Code-Universal Garage Door Opener Sensors (CR2149)
  • The universal beam sensor works with all major brands of garage door openers
  • Chamberlain, lift master, craftsman, overhead (1995+), genie, challenger, Stanley, linear
  • Quick retrofit installation. Non-polarized, so there is no way to hook them up backwards

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Chamberlain / LiftMaster / Craftsman Garage Door Safety Sensors G801CB-P

While this option isn’t universal, the G801CB-P is your best bet for working with Chamberlain, LiftMaster, or Craftsman garage doors. That covers the majority of garage door openers in use in the United States, so this is still a good option.

This set of sensors comes with mounting brackets, and 18 inches of extension wire to make the connection a bit easier. 

If you have a garage door from one of these three brands, I recommend buying the G801CB-P over the CR2149. This option doesn’t have the occasional alignment and light sensitivity issues that a few users of the CR2149 report experiencing. 

Chamberlain / LiftMaster / Craftsman Garage Door Opener Replacement Safety Sensors (G801CB-P)
  • Replaces defective or damaged sensors for every Chamberlain/LiftMaster Garage Door Opener manufactured after 1997; Not compatible with craftsman 100 series
  • Easy setup: Includes 2 sensors, mounting brackets, 18 inches of extension wire and instruction manual
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This site contains product affiliate links. We may receive a commission if you purchase after clicking on one of these links. As an Amazon Associate I earn from qualifying purchases.

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Tim Wells

Tim Wells, the founder of Garage Transformed, has been featured in dozens of home renovation publications, including, Home Stratosphere, House Digest, Livingetc, and SFGate. Since 2018, he has helped over two million people transform their everyday garages into something they can be proud of. He lives in Central Florida with his wife and bulldog.

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