How Does A Garage Door Sensor Work?

When you think about why a garage door isn’t functioning correctly, the first part you might look at is the motor. However, many times, the part you should look at is the sensor. How does a sensor on a garage door work and why do garage doors have them?

Safety Concerns

Due to safety concerns, regulatory laws were passed in the 1990’s to mandate safety standards for garage door installers. These safety measures were made in order to cut back on the number of accidents that occurred when a garage door was closing. These laws were implemented in the 1990s most garage doors you see today have been installed to federal regulations, all of which now include garage door sensors.

“Photo Eye”

Though almost every garage door sensor is interchangeable with the next, many people still don’t know how they work. In most cases, these companies implement the use of a “photo eye” system with their door opening mechanisms.

The main purpose of the system is to ensure that there is not anything blocking the path of the door when it is closing. It works by having each base station’s camera look for a sensor on the other base station.

If the line between the two “photo eyes” system is broken the door will stop. In order for the door to continue closing, the photo eyes must “see each other”. This is a loose way of saying that the ray of the infra-red beam that connects the photo eyes to each other remains uninterrupted. If that ray has been interrupted, the garage door will reverse, opening instead of closing.

If your garage door is not shutting or starts to shut, but then reverses and goes back up, there is a good chance your sensors are malfunctioning. The best thing to do is check the base stations of the photo eye system. They sit approximately two inches off of the ground. If the sensors are malfunction one of the base stations light will start to blink.


Another issue could be that there is an obstruction that is breaking “line-of-sight” between the two base stations. If the doorway is clear, you may need to clean the lens or realign the base stations as one of them may have been knocked out of position.

If all of these options fail, contacting a professional is going to be your best option. When that time comes, Sears Garage Doors is here to help!