Garage Door Sensors: Everything You Need To Know


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 it’s 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 the entrance of your garage to the sensor on the other side. The sensors are normally 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 isn’t able to 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.

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 at a different angle 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 motion of the door 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 damages and scratches
  • Preventing you and your family from entrapment or serious 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.

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 properly too. Usually it’s just some small cleaning and adjustments because the sensors are pretty 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 and 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 all-purpose cleaner to get the sensors to work.

It’s a good idea 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 that gets in your garage, you may need to do this more often.

Out of alignment 

Whether your sensors’ system boasts two sensors 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 you are 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 on, the circuit is aligned, and you can secure the devices.

Something is blocking the door 

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 easily pile up in front of the sensor. If you have a lot of foreign objects blowing into our garage, 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 with. 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)
$39.30
  • 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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01/23/2022 12:06 am GMT

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, as well as 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)
$48.06
  • 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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01/23/2022 12:07 am GMT

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