5 Main Reasons Why Garage Door Sensor Not Working

For almost thirty years, the law requires that garage owners have safety sensors installed in the garage. There are two of them, one on each side of the garage entrance. Their purpose is to stop the door from closing if there is an obstacle under them.

That way, the sensors cut the risk of injury and damage to your car and other objects found on the way to the door. However, when the garage door starts to malfunction, it interferes with the garage’s daily use. You probably wonder how to tell if the garage door sensor is bad and look for the best way to resolve this problem. Let’s see.

Garage doors sensor problems

1. The Garage Door Won’t Close

The first sign that something is wrong with your sensor in the garage is the garage door malfunction. If the door opens without problems but has difficulties in closing, something is wrong. Another option is that the door closes but reopens immediately.

In both cases, something interferes with the sensors, and they react as if there is an obstacle between them. That is why the door reopens to prevent an accident that can damage an object or injure the person under it.

There are several reasons why the garage door doesn’t open and close appropriately. Firstly, you should quickly check if there is a problem with the sensors. One of the simplest ways is to test them with a few cardboard boxes.

Cardboard box test

You should take a few cardboard boxes and place them under the open garage door to check if the garage door sensors work correctly. Since the sensors are about 6 inches (15 cm) away from the ground, you should choose boxes higher than that.

Now, you can try to close the garage door. If the sensors are in alignment and function properly, the boxes should interrupt the beam of light between them, and the door remains open. Another option is for the door to start closing but then open before touching the boxes.

However, if the garage door sensors are bad, the door won’t stop until reaching and damaging the boxes. It is possible that the door entirely closes as if there are no boxes and destroys them. Additionally, it can close partially and reopen after hitting the boxes. In both cases, the sensor security function has failed.

If the door destroys the boxes when it closes, switch to manual operation. Since there is no way to predict whether and how the door can slam without registering small obstacles, children, and pets, you should shut the garage door and don’t use the garage until solving the problem. That way, you will avoid possible accidents.

2. The Photo-Eye Sensor Lights

The Photo-Eye Sensor Lights

The photo-eyes sensors on the door’s track are approximately 6 inches (15 cm) above the ground. One sensor has a green and the other a red LED light. A green light on the sensor means that it sends a beam of light, while a red light indicates that it receives it.

If something is wrong with the sensors, one of these two lights goes out or blinks. That usually means something interrupts the light signal between them, or sensors are not on the same level. In both cases, they can’t perform their function correctly.

If the red light flashes and the green one works without problems, it means that the sensors are not in the alignment. It would help if you realigned them by moving them slightly until the moment both lights are on.

However, you should check whether you have a problem with the sensors only in a certain part of the day. Sometimes the sun makes a problem with sensors. If the sun’s rays fall at a certain angle on one of the sensors, they will interfere with the beam of light and cause malfunction.

A simple solution is to shield the sensors from the sun’s rays by placing cardboard in front of them. Always put the cardboard carefully so that it doesn’t interfere with the signal between the sensors. Otherwise, you can only replace one problem with another.

3. Sensor Lenses

Sensor Lenses

If you live on a busy street and the garage door is often open, dust and dirt will accumulate on the sensor lenses daily. As they are pea-sized, they easily get dirty over time and stop sending the signal necessary to close the door.

You can quickly establish a blocked signal as soon as you wipe and carefully clean the sensor lens. Take a broom, remove the cobweb around the garage door, and then use a soft cloth to remove the accumulated dust.

Repeat the test with the cardboard boxes to make sure that you have solved the problem. You need to check if the sensors have an uninterrupted signal so that the door opens and closes as before.

Besides, excessive humidity can interfere with sensor operation. If you live in a rainy area, you can expect that tiny drops of water penetrate the sensor. First, wipe the sensors with a dry cloth on the outside. Then, unscrew the metal holders and check if they are wet on the inside.

Another reason for moisture in the sensor’s lens can be lawn sprinklers. If you place the sprinklers too close to the garage, water can cause the problem. Solve it by moving them so that not a single drop can reach your garage door.

4. Sensor Power Supply

Sensor Power Supply

The green light on the sensor always shows that there are no problems, and everything is fine with the power supply. If both lights on the sensors are off, you will know that sensors have no power and can’t respond.

You should also check if the cable is unplugged, so the garage door doesn’t close. The fuse can blow due to voltage drop, or that power outage occurs. Once the power supply is established again, the sensors will become operational again.

5. Sensor Wire Damage

Sensor Wire Damage

One of the most severe problems with sensors on garage doors is wire damage. Depending on the garage door model, a sensor that flashes orange instead of the regular red light may indicate this kind of issue.

Carefully inspect all wires leading from the sensor to the terminal on the back of the opener. If the wires are tangled, unweave them and check if any of them is broken or twisted.

Sometimes, you can spot a staple or a nail cut through the wire insulation. All the wires need to be intact for the door to work correctly, and you need to connect them properly to the garage door opener. Keep in mind that you should connect the white wires to the white terminal, and the black and white wires to the gray terminal.

If you spot that wires are in the wrong place or broken, you should call an electrician to solve the problem. You can fix the sensing wiring yourself, but only if you are skillful enough.

Otherwise, incorrectly connected wires may result in electric shock. Besides, there can be significant malfunctions of the garage door opener, which would result in additional costs.

Garage Door Sensor Replacement

When the door doesn’t close persistently, and the sensors don’t light up, it is time for a sensors’ replacement. Clean them thoroughly and then check the wiring once again. If the problem still exists, the safest solution is to install new sensors.

On average, the price of the new sensors is from $75 to $90. However, you need to add the service cost to the final sum. If you call a professional to install a new pair of sensors, your overall cost will be around $200.

If you decide to replace bad sensors on your own, you need to disconnect the power first. Then, pull the sensors out of their braces and cut the wires near them so that you can connect the replacement ones.

Carefully connect the white wires on the sensor to the wires on the white terminal. After that, you need to attach black and white wires to the gray terminal. Don’t be surprised if your model has gray wires. Actually, if it is the case, it will further simplify the process.

Slide back both sensors into a metal bracelet and screw them on. When you plug back the garage opener, make sure they align correctly. Don’t forget that one sensor should be green and the other one red.

All you need to do is to open the garage door and repeat the test with the cardboard boxes. If you have done everything right, the garage door will stop before hitting the boxes and reopen right away. That means that you have solved the existing problem and the garage is safe to use.


The garage door sensors have a safety role. They prevent the door from closing while an object or person is underneath. Therefore, it is crucial to discover if the sensor is bad before hurting anyone or making damage. Once you notice that the lights on the sensors work improperly, you will know that there is an issue you need to fix.

8 thoughts on “5 Main Reasons Why Garage Door Sensor Not Working”

  1. It’s good to know that the sensor that flashes orange or red means there is an issue. Last night, my garage door wouldn’t close when I pushed the button and I’m worried that something broke. I’ll have to call a professional to fix my garage so I don’t get things stolen.

    • The sensors on my garage door are 2 different colors, one green, and the other yellow, and it’s not blinking. I cleaned the sensors up, but still, the garage door closes, but after a couple of seconds, it Re-opens. Please help!

  2. Garage door sensors work when.close.each other when.split to edges of door do not work. Old sensors did not work, new sensors do the same.

  3. Helpful article for installing and maintaining the garage door sensors. The indicator lights of the sensors will help anyone to find out the condition of the sensor.

  4. All the articles did not answer my problem with the garage door issue. My problem is , when I closed the door the light on the opener stay on for a while and turn off by itself. But the thing is my both sensors are off too. When I open the garage door again both sensors lights are lit. Is this issue apply to the bad sensors?


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