Though a garage door may look like a simple mechanism—how much complexity does it take to mechanically raise and lower something, really?—it’s made of a variety of moving parts, each integral to its functioning. Your garage door springs, for example, help shoulder the weight of the heavy door, and your garage door cables hold the two together.

While the intricacies of modern garage doors and garage door openers have made some stunning machinery, it also means that quite a bit can go wrong with your garage door if you aren’t prepared or knowledgeable about its functioning. We touch briefly on this topic in our garage door installation blog “Three Common Garage Door Problems and Causes.”

Today, though, we’re here to do a more detailed look at a common, yet incredibly frustrating issue: blocked sensors. When not taken care of, they can outright stop your garage door from closing!

What Is a Garage Door Opener’s Sensor?

To understand what it means to have a blocked sensor, it’s of course important to understand what a garage door sensor is in the first place.

To put it simply, your garage door’s sensor is a device that projects a thin beam of infrared light across the space where your garage door closes. If something steps in front of this light, it prevents your garage door from closing on top of it and damaging what’s underneath. Its primary units are two small “lenses” placed near each lower corner of your garage door, often coupled with a small light that indicates if the device is working.

Before you bypass this post entirely because you “don’t have a garage door sensor,” know this: there’s a long history of federal legislation surrounding these devices and a long history of suburban deaths before they became well-used. Chances are, your garage door has one—and chances are it will, at some point, become blocked.

What Is a Blocked Sensor?

When sensors function as they should, they’re an important piece of your garage door’s safety system. Because of them, you never have to worry about anything getting crushed beneath a machine part that can weigh two-hundred pounds or more!

Unfortunately, they’re fallible. While they’re a great protective mechanism, if the beam of light between the two units remains consistently interrupted when it shouldn't be, your garage door will be stuck open, as the machine will perceive it unsafe to close—even if there’s nothing in particular that warrants protection below it. This is known as a blocked sensor.

What Causes a Blocked Sensor?

A huge variety of things! The good news is that most of them are simple fixes. For example, items in your garage can trip the sensor if pushed into its path and left there. In this case, you wouldn’t need to call a garage door repair technician; simply clear the area below your garage door and try to close it again. If obstructions were the problem, you’ll then be home free.

A dirty photo eye can also be considered a blocked sensor in a way, as it’s dust and grime that are “blocking” the path of the infrared light. Wipe off the two small lenses that are attached to your garage door sensor; if your garage door closes normally, you’ve solved the problem.

Finally, sunlight, at the correct angle, can “block” your sensor from functioning. Because the sun emits infrared light just like your sensors, it can essentially “scramble” their signals, preventing the machine from communicating with itself, so to speak.

This can be a simple fix, depending on your garage door’s unique anatomy. Sometimes, a garage door repair specialist will simply need to switch the transmitting and receiving sides of the sensors; other times, they may install a special product to block the sun. Toilet paper tubes can be a short-term solution until a pro arrives, but they certainly aren’t visually appealing, nor will they last.

How Do I Know if It’s a Blocked Sensor?

Generally speaking, the primary symptom of an ailing garage door sensor is your door’s failure to close, so if that’s the case for you it’s a good problem to look into. Your sensor itself may also display warning signs in the form of flashing or off-color lights. Finally, if your garage is crowded with belongings, you may also consider tidying up a bit, as it could be a sign your sensor is blocked.

It’s important to note, though, that a garage door that won’t close isn’t only caused by a blocked sensor—so never try to force closed a garage door that’s sticky. Anything from bent garage door tracks to a misadjusted limit sensor can be the cause, and some of these issues are dangerous for the layperson to try and tangle with. Always call a garage door company if you can’t easily resolve the issue.

Door Power: One Garage Door Company for All Your Needs

Our Norwood team’s comprehensive knowledge of garage doors, from maintenance to repairs to installation, means you’ll never need to save the phone number of another garage door company again. Give us a call today at 952-467-3199.