How to Tell If My Garage Door Sensor Is Bad

How to Tell If My Garage Door Sensor Is Bad?

The automatic garage door is a blessing for us. We go through the door with our hands full of things without worrying about a thing. Also, parking the car inside has become a safe and smooth process.

However, recently, the door has been malfunctioning a bit. We wondered if the sensor had gone bad or not. But there was not much info around regarding how to tell if my garage door sensor is bad. So, we had to rely on a garage door mechanic.

After sitting on a discussion with the professional, we got to know many things that give away whether the sensor is functioning correctly or not. And through this article, we plan to help a person facing the same problem. So, if you want to diagnose the sensor accurately, stick till the very end.

How Do I Know If My Garage Door Sensor Is Bad?

A bad garage door sensor can cause a lot of problems. At some point, it can stop taking readings, and you might find yourself stuck outside the home. That being said, these are the things that you can do to test out the sensor:

How Do I Know If My Garage Door Sensor Is Bad

Step 1: Get Yourself a Common Everyday Object

First, you need to get something like a cardboard box or any sort of container. Make sure that it is large enough to reach the sensor and can come in the way of the sensor of the door.

Step 2: Place the Box on the Line of the Sensor

Open the door up and place the box right beneath the door. Try to close the door while the cardboard is in place. If the door closes completely, the sensor has gone bad. And if it does not close all the way and reverses automatically, then the sensor is absolutely fine.

Step 3: Check the Indicator Lights

If you are not yet capable of determining whether the sensors are working optimally or not, you need to check the indicator lights. These LEDs will be present on each of the sensors. Locate them and check whether the LEDs have a green light or not. If it is not green, then there are some problems with the device.

Check the Indicator Lights

Common Garage Door Sensor Problems

When the garage door sensors do not work as they should, it usually gives a couple of signs. Those signs would give away that the door sensors are unreliable, and you need to check them as soon as possible. So, without further ado, allow us to go through the signs of the garage door sensors not working optimally.

Common Garage Door Sensor Problems

Garage Door Sensor Flashing Red

The light indicator is there for a reason on the sensor. It states the condition of the whole internal and external parts. You might notice the garage door sensor blinking red light.

This blinking state of the light tells that the sensor is not aligned correctly. On the other hand, if the LED lights up green, the sensors are correctly aligned.

Garage Door Sensors Not Lighting up

In some instances, the garage door sensor might not light up at all. This condition means that there is some wiring problem. It can be a short or an open wire. You can also tell whether the wiring is correct or not by taking a look at them. If they seem damaged, the sensor will not operate at all. Thus, there will be no light.

Garage Door Sensors Not Lighting up

Dirty Lenses

Another sign that tells whether the sensors are working optimally or not is the lenses. If there is too much dirt and debris build-up on the lens, the sensor will not be able to pick up anything. And when it does not pick up anything, it will not be capable of controlling the motor.

How to Fix a Garage Door Sensor?

Now that you know about the common problems or signs that the sensors exhibit when they are not functioning optimally, you would want to know the ways to fix them, right? Well, these are the steps you should follow in that case:

How to Fix a Garage Door Sensor

Step 1: Check the Lens

First and foremost, you would want to check the condition of the lens. If it is dirty or has anything on the top, cleans it using a soft cloth. The dirt, grime, and dust build-up will block the sensor and prevent it from picking up anything. In fact, even when there is no dust or grime visible to your eyes, you should clean it.

Sometimes, the surface of the lens might be totally okay, and the sensors can get blocked because of an object placed in front of them. Make sure that the line of sight for the sensor is clear. Move anything that might be in front of it.

Step 2: Locate the Wires and Check Them

After checking the lens, you should check the wire. First, check if the cables are intact or not. Ensure that there is no breaking, opening, or looseness on the wire. Also, follow the wire and check whether they are connected to the controller box or not.

Locate the Wires and Check Them

If you find them disconnected, refer to the user manual and open the box. Make sure that you are exercising extra precautions while working with the breaker box. Connect the wires properly and move along to the next step.

Step 3: Check the Alignment

Now, you need to check the alignment of the sensors. For some models, when the alignment is off, the indicator light will start blinking. Usually, the color of the light will be red. Follow the user manual and adjust the alignment accordingly. You can take the help of alignment tools if necessary.

Furthermore, you should make sure that all of the sensors are facing each other. They should not be facing the opposite way. Also, make sure that the mounting mechanism or the bracket is installed in the right way.

Step 4: Allow the Moisture on the Sensor to Dry up

In extreme cases, moisture might build up inside of the sensor. When there is moisture dust and grime build-ups, and the sensor does not pick up anything correctly. Disassemble the sensor as much as possible and keep it somewhere that is dry and has a low moisture content in the air.

Allow the Moisture on the Sensor to Dry up

Allow the moisture to completely dry up and place the sensor back into the position. Carry out the same sensor test as we have mentioned in the beginning and now, check whether the door is working optimally or not.

Should Both Lights Be Green on Garage Door Sensors

The LED indicators on the sensors play an essential role. They basically state whether the device is working optimally or not. But to understand the LED properly, you need to have proper knowledge regarding the different states they remain. So, in this segment, we will discuss all of them:


The green light states two things. Firstly, it tells you that the power is on and the wiring is correct. In other words, the installation was a success, and the device is getting the energy it needs to operate.

Lights Be Green on Garage Door Sensors

Secondly, it states that the alignment of the sensor is correct. For that reason, both the lights of the sensors should be green. Also, the green light might blink when it is receiving signals.


Some of the models will have two LED indicators. One will light up green, while the other one will light up yellow. The yellow light will not light up all the time. It only glows up when it is sending signals. So, you can tell that if there are two lights available in one sensor, both should not really be green.

Lights Be Yellow on Garage Door Sensors


As you can tell, red light means that there is something wrong with the sensor. Depending on the model of the sensor, it can tell two things. It can state that the wiring of the sensor is not correct. In other words, it is not receiving the proper amount of power, or there is a short in the wiring.

Lights Be Red on Garage Door Sensors

On the other hand, it may signal that the alignment is off. While the red LED is on, the sensor will not operate optimally at all. You would need to check the alignment and wiring properly to make it work.

No Light

In some cases, there might not be any light at all. This means that the sensor is not receiving any power. Check the wiring and ensure that it is correctly connected to the control box. Also, make sure that the cable of the control box is connected to an outlet.

Final Words

Hopefully, you got to know all that you were looking for regarding the topic of how to tell if my garage door sensor is bad or not. If you are noticing any problem, refer to the signs that we have discussed above.

Then, carry out the troubleshooting steps. If those do not solve the problem, it would be time to call the manufacturer. Get a replacement or claim the warranty if there is any.

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