Garage Door Sensors: Everything You Need To Know

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 those sensors work, the different types, and why you need them. Finally, we’ll look at our recommendations for universal garage door sensors if you need to replace yours.

How Do Garage Door Opener 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. If you have never looked into how this technology works, it can seem rather complicated at first glance. 

Garage door sensors work by shooting a beam of infrared light 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. As long as the beam isn’t interrupted, the door will open or close normally.

The infrared beam from the garage door opener sensors can’t be seen by human eyes. So don’t look for any red laser lines like you see 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, it helps to understand their differences so you can 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, it breaks the connection between the two units. The sensors then send a stop signal to the electric motor of your garage door.

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Retro-reflective Safety Sensors 

These 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 the beam of light that crosses the garage door. There’s a retroreflector on the other side of the garage door to reflect the light ray directly to the receiver element.

When something is in the way of the sensor and the retroreflector, the beam loses some of its strength. The beam is partially reflected and hits the sensor different angles and strength.

Why Do You Need Garage Door Sensors?

The short answer is because 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 simultaneously making the garage doors more convenient and efficient.  

Besides being the law, installing safety sensors have 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. Sensors lower the risk of harm.

Although its 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 sensors haven’t experienced a significant failure, you should be able to quickly troubleshoot them and get them working in no time. 

Here are the most common issues that 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. If you have a lot of dust in your garage, you may need to do this more often.


Whether your sensors system boasts two or only a sensor and a mirror, they need to be perfectly aligned to work. 

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 in turn until the power-indicator lights, which can be either green or red, are both on and the same color.
  3. Once the indicators are on, the circuit is aligned, and you can secure the devices.


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

I’m betting that it’s easy to see if a child’s tricycle is in the way. 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

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 that 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 truly universal, the G801CB-P is your best bet if you’re 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 pretty 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, as 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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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.