How To Test Or Troubleshoot Your Garage Door Sensor?

By Sarah Spoonhoward | Export

May 25

Does your garage door refuse to open? Or does it stay open all the time? A malfunctioning garage door sensor can cause a variety of problems, not to mention the frustration.

Malfunctions turn that convenient, time-saving garage door opener into a problem. Often, an expensive service call may seem like the only solution. But get this -- you can find and fix many common garage door sensor problems yourself. In fact, it’s often easy.

Although you’re dealing with a fairly complex electronic contraption, most issues are simple, and it’s usually not about damage to the garage door sensor itself. Stick with us, and hopefully, we'll save you from wasting your time and money on a service call you don't really need.

Reasons to Check Your Garage
Door Sensor Yourself


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Since your garage holds your car and other valuable things you need access to every day, being able to get in and out and prevent others from doing so is an urgent matter. It’s often faster to troubleshoot things yourself than wait for an expert to arrive and inspect your garage door sensor system.

What’s more, finding and fixing garage door sensor problems is usually simple and costs little to no money. If you’ve ever had a professional take a look at something broken only to fix it in seconds and leave you thinking you could have done that yourself and saved a pretty penny, you know what I’m talking about.

How to Troubleshoot Your Garage Door Sensor

When garage door openers act up, there could be a few different reasons. Regardless, troubleshooting your garage door sensors is straightforward once you know where to look. Let’s look at the various signs and tests you should consider.

Checking your remote and wall switch

Checking remote

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First of all, it’s essential to find out whether it’s the sensor acting up or just a switch before you start looking for more serious issues. Your batteries may be dead, and then the transmitter can’t send the signal to open your garage doors. Or some piece may be missing. Starting at this end can save you much time and effort.

Check the wall switch and try your remote at different ranges to establish whether it’s a problem with the remote. If neither works, something else is wrong. However, if the wall switch works, this indicates that something’s wrong with your transmitter. If it’s the other way around, the wiring may be bad. Let’s look at each problem separately.

Fixing the transmitter


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It the transmitter is merely out of battery power, it’s best to replace the battery in all your transmitters. You’ll probably need a small screwdriver for this task. If you replace them and the problems remain, there are a few other things to consider.

Another thing that’s easy to overlook is the transmitter range. It may not reach as far as you think, and there can be a few reasons for this. Also, there could be something blocking the signal. For example, concrete walls and certain woods can prevent the signal from reaching your garage door sensor. Therefore, it’s wise to wait until you reach the driveway before trying to open the garage. However, if you’ve noticed a loss of range and a battery replacement doesn’t correct it, there are other issues to look for.

It’s possible that the garage door sensor antenna isn’t hanging properly, which can shorten the range or prevent the receiver from working. Something may have moved it or tangled it up, and it’s hard to spot if you’re not searching. It should hang down, and nothing should obstruct the path between the garage door sensor and the transmitter. Also, check the antenna for damage while you’re at it.

Unwanted opening and closing

Unwanted opening and closing

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Some people experience garage doors opening and closing for no apparent reason when they aren’t pressing any buttons. There may be something wrong with the wiring, but it could also be a jammed remote or a stray signal.

First, you’ll want to check the remote for damage or stuck parts. If something’s holding down the button or otherwise completing the circuit, it can activate your garage door sensor. Also, inspect any spare transmitters you have and make sure that nothing’s triggering them.

Another possibility is that your neighbors have their garage door sensor operating on the same frequency on yours. That means you can open and close each other’s garage on accident when you open your own. You can always change the frequency, and it won’t be very hard. However, you’ll have to find the instructions in your manual since makes and models differ.

If the problem remains, the next step is to reset or reprogram your transmitter. This procedure also varies depending on your specific garage door sensor. In general, there will be a reset button or a learn button. To reprogram your transmitter, you press and hold this button down for a while. Many models give you a blinking light to let you know you’ve held it long enough. Then you push the remote opening button, and the garage door sensor system resets.

If none of these fixes helped, you might need to contact a professional to look at your garage door sensor. But first, you should look for different causes using the following troubleshooting tips.

Addressing the wall switch

wall switch

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While it’s not as common, your wall switch may sometimes start acting up while the remote still works fine. Or both may fail due to a problem with the garage door sensor or something else. The first thing to do is verify whether it’s a garage door sensor issue or a broken switch.

You can check this by removing the switch from your garage wall and releasing the wires from it. Next, you can touch the wires together to complete the circuit. Since garage door openers operate on low voltage, this is perfectly safe. If connecting the wires manually works and the switch doesn’t, it’s a faulty switch. You can replace it with something similar, such as a doorbell switch, or order a replacement.

If this doesn’t work, you’re dealing with a bad wire or a serious problem with the garage door sensor or the opener system itself. You’ll want to get professional help with this.

Inspecting the photo eyes


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Is your garage door opening fine but refusing to close at times? This could indicate a problem with the safety photo eyes. You find these sensors on the sides of your garage entrance, and their purpose is to stop the door from closing if something’s in the way. Since 1993, this is a standard feature to prevent injuries and damage caused by doors closing onto someone or something.

This system works by emitting a beam between the photo eyes. When something breaks the beam, the door cannot close. Therefore, anything that can interrupt the beam may cause false positives. For example, dirt on the lens can be hard to spot, but it’ll send the signal that something’s blocking the entrance. Another issue is that mild bumps and vibrations may cause a misalignment over time, and then the beam won’t connect the eyes.

If you experience this issue, it’s time to clean the photo eyes. You must be careful to avoid scratching the lens since that can cause further problems. It’s best to use a gentle cleaning agent that won’t leave streaks. Be gentle but thorough, and wipe away any excess liquid left behind to prevent dust from sticking to the newly cleaned garage door sensor.

If cleaning and drying the lens didn’t fix the problem, there’s probably an alignment issue. They must point the right way at the right angle, and it takes a lot of precision. A slight difference between the two eyes is enough to give a false positive. To fix this, you’ll need a tape measure and a level, ideally a laser level. Measure the height from the ground and ensure that it’s identical for both eyes. Then, use the level to make sure that they point right across at each other.

Checking the wiring

Checking the wiring

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If you’ve tried everything so far and you’re no wiser about what’s wrong with your garage opener, it’s time to check the wires. Don’t worry; many wiring problems are simple to troubleshoot without the help of an expert.

To begin, look for damaged wires. Also, look for any spots where staples or clamps may pinch a cord. Pinching cords can force the wires together inside and cause a short circuit. Releasing tight staples and sharp bends can solve the issue, but sometimes you must replace the wiring.

Next, try nudging and wiggling cords while activating your garage door sensor. Sometimes, a loose connection or slight damage can cause the wires to only complete the circuit in specific positions. If you find this to be the case, you can sometimes fix the problem by bracing the cable in the right position. Other times, you need to replace it.

If it’s an old system, consider replacing the whole thing. You can take a look at the best garage door openers here.

Final Thoughts on Troubleshooting
Garage Door Sensors

Now you know how to troubleshoot your garage door sensor. If none of the above methods help you find the error, it’s likely that your garage door sensor or other components of your garage opening system are damaged. It’s best to call a professional and get the required parts and services.

Transmitters and sensors aren’t the only parts that can act up. You may want to read more of our troubleshooting and maintenance tips and tricks. Thank you for reading, and good luck.

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