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This is a woman controlling the garage door with a remote from her car.

Garage door sensors offer a safety feature that prevents people or objects from getting caught underneath your garage door while it is closing.
The garage door sensors utilize infrared technology to create a line of sight between two sensors on either side of the garage door. If the line of sight is interrupted, the door will reverse and reopen.
Garage door sensors can malfunction and may need to be repaired or replaced from time to time. There are also many variations of garage door sensors that can protect you from other potentially dangerous situations, such as filling your garage with dangerously high levels of carbon dioxide.

Garage door sensors are a great safety feature to help avoid common accidents that can occur while your mechanized garage doors are closing, but how do garage door sensors work? How was this safety mechanism designed, how do you know if your system is malfunctioning, and how do you repair it?

How Do Garage Door Sensors Work?

This is a close look at the one receptor eye of a garage door safety sensor that stops action if the beam is crossed.

Garage door sensors have been a mandatory safety feature that has been incorporated into federal regulations for automatic garage door manufacturers and installation companies since the 1990s. They are almost ubiquitous in our homes these days, but some people still don’t understand how they work.

Typically, a pair of garage door sensors will weigh approximately 0.6 pounds and will be mounted across from one another on either side of your automatic garage door. They are mostly made of plastic, with glass, metals, and other electronic elements that support the infrared sensors used.

This is a close look at the motion sensor device for automatic gate opening.

They typically measure at roughly 2.5 x 2 x 2 inches, and the style has remained somewhat unchanged since the 1990s, except these days they are equipped with better, more reliable, faster technologies that require far less space than they did in the past and are significantly easier to install, due to wireless technology.

The primary function of the infrared “eyes” on either garage door sensor is that they need to ensure that nothing is blocking the door’s path as it closes. If something breaks the line of sight between the sensors, it means that something is in the way, and the garage door will automatically stop closing and reopen. This safety feature prevents people, objects, or pets from getting stuck underneath the door and causing harm or damage.

Garage door sensors are now mandatory for installing all Automatic garage doors after compliance regulations were introduced at the federal level in the 1990s.

This is a look at the opening door and automatic garage door opener electric engine gear mounted on ceiling with emergency cord.

For the garage door, which is also opened with a remote that uses an infrared system of its own, to continue closing, the eyes on the sensors must “see” each other at all times. If interrupted, the door, opened and closed through a mechanized pulley system, will reverse.

Types of Garage Door Sensors

This is a man installing the automatic garage door opener and sensor.

Safety sensors

When we talk about garage door sensors, we typically associate them with the safety sensors we’ve already described. They’re designed for safety and to protect anything from being crushed under the garage door as it’s closing. However, there are other types of Grage door sensors that offer safety mechanisms.

Monitor sensors

Monitor sensors are another type of garage door sensor that is more of a device to alert you when the garage door is left open or unclosed. They allow you to set a time for how long the garage door can be left open and set it to automatically close, or you can be alerted through a panel and close it yourself, with the sensor serving as a mere chime to remind you to close the door.

CO₂Sensors

These are among the most advanced forms of garage door sensors currently on the market. CO₂ sensors are designed to measure the potency of carbon dioxide in the air in your garage. And, if your garage is filled with dangerous levels of CO₂, the doors will automatically open to let the CO₂ out and let fresh air in.

Alternatives To Garage Door Sensors

This is a close look at a man opening his garage door by hand with a handle.

Unfortunately, there aren’t any alternatives to garage door sensors other than to switch to a manual system – gates and doors that you’ll have to get out of your car to open and close.

Since garage door sensors are now federally mandated in compliance laws, you cannot escape using them if you want automatic garage doors.

But, if you truly hate them, you can opt for the manual option with a good old chain and padlock. You can have doors that slide vertically, horizontally, that fold into panels, or that swing open. But they will not have the aforementioned mechanized pulley system that’s not only good for your safety and protects you from carjacking but is also incredibly convenient, particularly on freezing winter mornings and evenings.

Pros and Cons of Garage Door Sensors

A man is controlling the garage door with his remote.

Garage doors, by design, are supposed to be there to keep you and your family safe, and garage door sensors are part of the package.

Therefore, the biggest advantage that they bring is assurances over your family. Where garage doors protect your home’s perimeter, garage door sensors protect you from your garage door.

The cons are that sometimes garage door sensors can be frustrating or serve as an inconvenience. Sometimes your garage door sensors may simply be malfunctioning, or the infrared eyes are dirty or need to be recalibrated. If the doorway is clear and your garage door still won’t close, you must clean the lens or realign the sensors. Should the problem persist, you should contact a professional to fix it.

And, especially with monitor sensors, sometimes you’re intentionally leaving the garage door open, perhaps because you’re working in there, and it can be really annoying to hear the panel chiming, telling you you’ve left it open continuously.

The History of Garage Door Sensors

These are old vintage wooden double garage doors with small windows.

With the invention of the automobile at the beginning of the 20th Century, people needed a place to store their cars while not in use.

Typically those who could afford cars at the time would have a separate storage area for their horse-drawn carriages that people used previously. However, those doors were manually operated and would typically slide horizontally or swing open.

CG Johnson invented a new garage door in 1921 that used a mechanized pulley system to pull the door upwards, fitting underneath the roof of the area that car owners stored cars their vehicles in.

This system was improved when Herbert Cady Blodgett joined Johnson to create the first electric door opener. The 1940s saw remote control sensors come to the fore, and over time they became a staple feature of garage doors, allowing people to open the doors without leaving their vehicle.

Garage door sensors were first experimented with as a safety feature after the invention of infrared technology in the 1960s, before becoming a mainstream feature in the 1990s.

What Do Garage Door Sensors Cost?

Garage door sensor prices vary according to types and brands, but a standard set of safety beams with mounting equipment will cost you around $30. Garage door monitor sensors cost a lot more, ranging between roughly $30 and sometimes as high as $130. CO₂ sensors usually represent good value for money at about $40, but you can pick up a low-quality product for as little as $25.

It’s not recommended that you opt for the cheaper options because you’ll end up replacing them more frequently and spending more in the long term.

Where to buy Garage Door Sensors

The driver gains access to the garage door with the use of a key card.

If you’re looking for reliable garage door sensors, you can ask for recommendations from your local hardware store, or you can explore your options on Amazon.

We recommend that you get the Digi-Code-Universal Sensors CR2149 Universal Garage Door Opener Safety Beam Sensor, an industry-standard and compatible with most automatic garage door systems. A quick, retrofit installation makes it a popular product, but they tend to be quite pricey.

Alternatively, the Chamberlain Group G801CB-P Chamberlain/LiftMaster/Craftsman 801CB Garage Door Opener Replacement Safety, Includes 2 Sensors, Mounting Brackets and Hardware, 1 Pack, One Color is smaller, more affordable, and is compatible with every Chamberlain Garage Door opener made after 1997, meaning there’s a good chance it will be compatible with your system because Chamberlain is the largest garage door manufacturer in the United States.

How Do Garage Door Sensors Work?

How Do Garage Door Sensors Work?