Why is My Garage Door Sensor Blinking Red – Fix it!


Hey there! Is your garage door sensor blinking red and giving you trouble? Don’t worry, you’re not alone! This is a super common problem that affects all sorts of garage door brands like Chamberlain, Liftmaster, and Genie.


But don’t stress, because I’m here to help you through what’s causing that blinking red light and give you some easy steps to fix your garage door.

Why is My Garage Door Sensor Blinking Red?

Garage Door Sensor Blinking Red

Pic Credit: AllGoodGarageDoor.com

First off, let’s chat about why garage door sensors are so important. They’re not just there for show – they play a crucial role in keeping you, your family, and your belongings safe.


They’re required by law in most states! These clever little sensors use an invisible infrared beam to detect if anything (or anyone) is in the way of the closing door.

If something interrupts the beam, the sensors tell the door to stop closing or opening to prevent any accidents or damage. Pretty nifty, right?

You Can’t Miss this: Why is My Smoke Detector Blinking Red

How Do Garage Door Safety Sensors Work?

Garage door sensors are like the dynamic duo of garage safety – they work together to keep you and your stuff out of harm’s way.


Here’s how it works:

  • There are two sensors, one on each side of the garage door tracks.
  • The sensors “talk” to each other using infrared technology.
  • When you close the door, the sensors shoot an infrared beam across the opening.
  • If anything gets in the way and breaks the beam, the sensors alert the garage door opener to stop the door from closing.

So let’s say you’re closing up the garage and oops – you forgot your bike is still under the door! As the door starts coming down, the sensor on one side will spot the bike, break the beam, and tell the opener to stop the door ASAP. Crisis averted!

5 Common Reasons Why Your Garage Door Sensor is Blinking Red:

Okay, so now that we know how important these sensors are, let’s talk about some of the common issues that can cause them to start blinking red:

Misaligned Sensors:

If your sensors are flashing red, there’s a good chance they’re not lined up quite right.


This means they can’t “see” each other properly because:

  • Something is blocking their line of sight.
  • They’re at uneven heights.
  • They’re not angled correctly To fix this, check for any dirt or cobwebs obstructing the sensors, then make sure they’re precisely level with each other and at equal distances.

Blocked Sensor Path:

Remember how I said the sensors need to “see” each other? Well, if there’s stuff in your garage blocking their view, that’s going to cause problems. It’s like trying to walk through a crowded room without bumping into anyone!

  • Maybe there are some boxes stacked in front of one sensor.
  • Or your kid’s bike is parked too close to the other sensor.
  • Even something small can trip up the sensors Move any obstacles out of the way, or temporarily cover the sensor until you can clear the path.

Dirty Lens:

Over time, your sensor lenses can get pretty grimy. Dirt, dust, and cobwebs can build up and block the infrared signal, which confuses the sensors and causes them to blink red. Imagine trying to see through a dirty windshield – not easy! To clean the lenses:

  • Grab a clean, soft cloth (microfiber works great).
  • Gently wipe away any gunk on the lens and receiver.
  • Use compressed air to blow debris out of hard-to-reach spots.
  • Repeat every few months to keep things running smoothly.

Loose or Damaged Wires:

Another reason your sensors might be on the fritz is because of loose or damaged wires. If the wires get disconnected, the sensors can’t communicate with the other electrical components and both lights will start blinking red.

  • Check all the sensor wires to make sure they’re plugged in securely.
  • Tighten or reattach any loose wires.
  • If you spot any frayed or cut wires, it’s best to call in a professional to handle things safely.

Faulty Sensors:

Sometimes sensors can go kaput due to physical damage, misalignment, or interference from other devices. Faulty sensors need to be replaced ASAP to keep your garage door working safely. Signs of a faulty sensor:

  • Visible damage to the sensor or wiring.
  • One or both lights are completely dark/not lit.
  • Sensors won’t stay aligned or respond to adjustments.
    To replace a faulty sensor:
  • Check for physical damage or obstructions.
  • Attempt to realign the sensors.
  • Clean the lenses thoroughly.
  • Move any interfering devices.
  • If none of the above works, it’s time for new sensors.

How to Tell if a Garage Door Sensor is Bad

Sensor Brand Indicator Light Location What to Look For
Liftmaster The side or bottom of the sensor Solid green = working, blinking red = misaligned or problem
Chamberlain The side or bottom of the sensor Solid green = working, blinking red = misaligned or problem
Genie The side or bottom of the sensor Solid green = working, blinking red = misaligned or problem

If your garage door sensor is bad, you’ll likely notice:

  • Indicator lights blinking red or off completely.
  • Door reversing or refusing to close.
  • Sensors that won’t stay aligned.

Always check your manufacturer’s manual for specific troubleshooting info and instructions.


How to Troubleshoot a Garage Door That’s Blinking and Not Closing?

Troubleshoot a Garage Door That's Blinking and Not Closing

Picture Credit: Rowedoor.com

Is your garage door stuck open, the light is flashing, and you’re scratching your head wondering what to do? Don’t panic! The first step is to check those all-important sensors. Here’s what to do:

Find the Sensors:

  • Look at the bottom of each garage door track near the ground.
  • Most sensors are located about 6 inches off the ground.

Check the Alignment:

  • Measure the height of each sensor from the ground.
  • They should be facing each other and perfectly level.
  • Gently adjust any crooked sensors until they’re lined up.

Give Them a Self-Test:

  • Look for the LED light on each sensor.
  • A solid green light means they’re working A-OK.
  • Flashing red or no light could mean misalignment or a problem.

Clean the lenses:

  • Inspect each sensor lens for dirt, dust, and pesky cobwebs.
  • Carefully wipe away any grime with a soft cloth.

Confirm the Alignment:

  • Double-check the height and angle of the sensors.
  • Use a level to verify they’re properly aligned.
  • Call in a pro if the sensors are damaged or weren’t installed correctly.


  • Q: Can I bypass my garage door sensors?

A: I know it might be tempting to bypass finicky sensors but trust me – it’s a bad idea. Garage door sensors are a vital safety feature required by law. Disabling them puts you, your family, and your property at serious risk. It’s just not worth it!

  • Q: Will LED light bulbs interfere with my garage door sensors?

A: Some LED and CFL bulbs can cause trouble with garage door sensors because they emit a small amount of invisible infrared light that the sensors pick up. If you suspect your bulbs are the culprit, try switching to a brand that’s garage door opener compatible or use a low-interference LED.

  • Q: How long do garage door sensors last?

A: With proper care and maintenance, garage door sensors can last a long time – we’re talking 10+ years in many cases. However, the lifespan ultimately depends on the brand, model, usage, and environmental factors. Regularly clean the lenses and check the alignment to extend your sensors’ longevity.

  • Q: Are garage door sensors required by law?

A: In most areas, yes – garage door sensors (also called safety reversing sensors or photo eyes) are legally required. This is thanks to the UL-325 standard introduced in 1993 to make automatic garage doors safer and prevent entrapment accidents. So not only are they a smart idea, but they’re also mandatory.

The Bottom Line

Whew, that was a lot of info! To recap, if your garage door sensor is blinking red, it’s probably due to misalignment, blockage, dirty lenses, loose wires, or a faulty sensor.

With a little troubleshooting and elbow grease, you can often resolve the issue yourself by realigning the sensors, cleaning the lenses, and securing any loose wires.


However, if you’ve tried all the DIY fixes and your sensors still aren’t cooperating, it’s time to call in reinforcements.

A professional garage door technician has the tools and know-how to diagnose and solve even the trickiest sensor problems.

The most important thing is to never ignore a blinking red sensor light! Your sensors are trying to tell you something is wrong, and putting off repairs could put you and your loved ones at risk.

Stay safe out there, and happy garage door troubleshooting!


You may also like...

Leave a Reply

Your email address will not be published. Required fields are marked *