Up. Down. Up. Down. That’s mostly what a garage door does. If it’s doing it safely, you’ve got your garage door sensors to thank for that.

However, if your garage door isn’t going up and down, then you’ve probably got a problem with your garage door sensors.

Garage door sensors are the lowly, often forgotten about, unsung heroes of your garage door. The garage door sensors are the reason why your garage door pops up when your kid runs under it while the door is lowering. But, the sensors can also cause a lot of frustration for owners when they malfunction.

What usually happens is the garage door stops lowering properly. It rises when you don’t want it to, like when you’re trying to get to work in the morning.

When that happens, the odds are pretty good your garage door sensors are the cause. Fortunately, there are several DIY ways to diagnose -- and fix -- the problem.

What Are Garage Door Sensors?

Your garage door sensors are the “eyes” of your garage door. If you look at the bottom of your garage door track, you should see two funky looking things attached to the garage door track (one on each side).

They should be about six inches up from the floor. Those are your garage door sensors, and they might look something like this:

Picture of garage door sensor. Image via author, all rights reserved

If you examine this picture closely, you’ll notice a few things. First, you’ll see a green light on this particular sensor. Each of your garage door sensors should have a light on it also.

One sensor has a green light, and one sensor has an amber or yellow light. It doesn’t matter which sensor is on which side of the garage. The important part is that you have one of each.

The other important part of the picture is the glass eye. It kind of looks like a mirror. That’s where your safety beam is.

The safety beam is the invisible bar that your garage door sensors create. If the door is moving and someone or something breaks that beam, your garage door will automatically rise, so it does not crush whatever is breaking the beam.

Signs and Symptoms of Broken Garage Door Sensors

Figuring out that you’ve got a problem with your garage door sensors is pretty easy. You press the button (either on the wall or the remote), and your garage door starts to lower. Then, for no apparent reason, it rises before it hits bottom like something broke the safety beam.

That can happen intermittently or continuously. However, problems closing the garage door do not automatically mean the garage door sensors are causing the problem. To figure out if it might be the safety sensors, test them.

When the garage door is open, close the door using the button in the garage. Instead of just pressing the button, hold it down. That tells your garage door to ignore the safety sensors. If the garage door closes, the problem is your garage door sensors. But, if it doesn’t close, it’s something else.

No matter what is causing your garage door issues, not being able to close your garage door is a safety issue. Fortunately, if the problem is your garage door sensors, it’s something you can easily fix.

How to DIY This

Old metal gate

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More often than not, whatever ails your garage door sensors is easy to repair yourself. In fact, many of the fixes don’t even require special equipment or even an in-depth knowledge of how to fix things.

They can’t see

Sometimes the most straightforward answer is the right answer.

Check around the sensors and see if anything is blocking them. It sounds obvious, but you’d be surprised what can “block” a sensor. Believe it or not, a small leaf can cause the beam to break. So can the way the sunlight hits the sensor

Check carefully around the sensor to see if there is something tiny you’re missing. Remove even the tiniest bit of debris that may be blocking the garage door sensors. If it appears that sunlight is the problem, considering getting a sunlight shade for the sensor to help alleviate the problem.

I have had similarly baffling issues. For instance, my old garage door sensors were a little sensitive. When it would snow big, wet, heavy flakes (more like snow chunks than snowflakes), my garage door would go up when I was closing it. The snowflakes were so big, it disrupted the beam!

As I said, you'd be amazed at what can block the sensor.

Bath time

Garage door sensors often malfunction because they are dirty. Look again at the picture. When the eyes are dirty, the beam can’t connect. If that’s the case, the sensor will assume the beam is broken when the garage door is moving and send the door up.

Cleaning garage door sensors is a pretty simple process.

Take a dry rag and wipe both sensors clean. Use a clean rag that is gentle on the glass. You don’t want to scratch the sensor. That will only cause more problems. Brush away any cobwebs or spiderwebs while you’re at it. As thin as they are, they will block the sensor.

And that’s it. Assuming dirt was the problem, you should have your garage door back.

Kiddie bike with four tires behind

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Light it up

So, you checked for small objects, and you cleaned the sensors, but your garage door sensors still won’t cooperate. Now what?

Remember the light from the photo? Good. One sensor should have a green light, and one sensor should have an amber or yellow light. It doesn’t matter which sensor is where. What matters is that you have one of each.

Ever sensor brand is a little different. However, in every case, you have one green and one yellow or amber sensor. If you check your sensors and this is what you’ve got, great. Your sensors are properly aligned. But, if you don’t have one solid green and one solid yellow light on each sensor, you’ve got sensor problems.

Funky frames

If you look at the picture again, you’ll notice that the sensor looks like it’s clipped onto the garage door frame. There’s a little more to it than that. But, as you can see the sensor sticks out from the attachment. It has to work.

However, to make it so the sensor can hang out like that, the mount has to be made from a lightweight material. Usually, that material is aluminum, and we all know how easy it is to crush an aluminum can.

Well, that’s the same issue here. While no one is going around crushing garage door sensor mounts for fun, that doesn’t mean accidents don’t happen. For example, a basketball bouncing the wrong way could damage the mount. Even accidentally whacking it with a ladder or even your foot could do it.

If that happens, your garage door sensors won’t align properly which means they will not work. So, you need to adjust the mount.

Most garage door sensors mount with a wingnut. You can see it in the picture. Loosen the nut with just your hand. If the clip (the part that’s attached to the garage door track) is out of whack, you may need a screwdriver to loosen it so you can adjust it.

In most cases, the mount isn’t damaged; it’s been knocked out of position.

Simply point the sensor back to the other one and make sure you’ve got the solid green light and solid yellow light. Once you’ve got that, you’ve got a perfectly-aimed sensor. Reattach the sensor, and you should be all set.

Advanced Fixes

Bike near a metal gate

Image source: Pixabay.com

So, you’ve done all of the above, and your garage door still isn’t working. If you’re up for it, you could try the advance fixed. What’s that? Inspecting, connecting, and possibly replacing the wires in the garage door sensors.

That is truly an advanced level fix. Beyond remembering to disconnect the garage door before you start this, this fix involves messing with the wires in the garage door sensors. If you do not feel qualified to attempt this, don’t! Call in the pros.

Check the wires

Raise the garage door then disconnect the power.

Take the back off the sensor. You may need to remove the sensor from the track to do this. Then, check the connections. Make sure the wires are plugged in all the way. Just like a stray basketball can knock the sensor, they can also jiggle the connections lose.

Once you’ve determined the wires are connected properly, reassemble the sensor and reattach it to the track. Make sure the sensors are properly aligned.

Give the garage door a test run.

Replace the wires

Graffiti on a green garage door

Image Source: Pixabay.com 

If that doesn’t work or you notice that one of the wires is bad, you can replace the wires yourself. However, this is only for handy folks who are comfortable with this level of DIY repair. If this doesn’t sound like you do not attempt this repair. Call in a professional.

To replace the wiring in your garage door sensor, start by disconnecting the garage door from the power, then remove the sensor from the mount.

Take the wire that’s attached to the sensor and detach it from the sensor. You’ll probably have to cut the wire. Then separate the wire. That sounds weird, but what you’re looking at is actually two different wires that are joined together. Splitting them makes them easier to work with.

Now, check out the two wires. You’ll notice that they are two different colors. One wire is white. The other is white with a black or grey stripe on it. Sometimes, you’ll get two entirely different colors, but white with white-grey is pretty typical.

Strip off the rubber from the “good” part of the wires. This is the wire that’s still in good shape and can be reused. Attach the new wires (making sure you match the colors). Twist the new wires to the existing wires and seal with black electrical tape. Reassemble the sensors and put them back in place.

​Time to Replace

If all else fails, it may be time for new one​​s. This is especially true if the light on one of the sensors won’t light up despite all of your tinkerings.

Personally, I’m calling the pros in on this one. But, if you’d like to fix this one yourself, here’s a nifty video that explains how:

​Don’t Neglect Garage Door Safety

White building with metal gate

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Judging by the amount of “how to bypass your garage safety sensors” videos that exist, many people don’t want to bother with the repair. However, your garage door sensors are an integral part of maintaining a safe garage door.

Without a properly-functioning garage door, you will always run the risk of the door staying open without you realizing it. Once that happens, your garage and your home are no longer secure. So, whether you DIY repair your garage door sensors or call in the pros, it’s something you’ve got to do to keep you and your loved ones safe.

Got any tips to share? Sound off in the comments below.

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