Why Your Smoke Detector is Blinking Red: Common Reasons

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Meanings for smoke detectors by Kidde, First Alert, and more

Co-authored by Saul Jaeger, MS and Hannah Dillon

Last Updated: June 8, 2025 Fact Checked

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• Most Common Reasons
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• Kidde Smoke Detectors
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• First Alert Smoke Detectors
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• FAQ

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Is your smoke detector blinking red and you're not quite sure why? A red blinking light might seem like a cause for alarm, but depending on the light flashing pattern and your smoke detector model, it could actually mean the detector is working normally. In this article, we go over the common reasons your smoke detector is blinking red, as well as the light patterns for Kidde and First Alert smoke detectors. Keep reading to learn more.

Why Your Smoke Detector is Blinking Red

The reason your smoke detector is blinking red depends on the model. If you have a Kidde smoke detector, it could be blinking red to show that it's powered on, that an alarm has been silenced, or that smoke has been detected. First Alert detectors blink red when an alarm is sounding or an alarm is silenced.

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Section 1 of 4:

Common Reasons a Smoke Detector Blinks Red

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1. 
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   The meaning of the red light on your smoke detector varies by model. Each smoke detector has different lights and alert patterns, so it's important to find the manual for your specific model to learn what the red light means on that device. In most cases, a blinking red light without a chirp or sound means the alarm is working properly and there's nothing to worry about. The most common reasons you'll see a red light on your smoke detector:

   • Your smoke detector is receiving power and working properly.
   • The smoke detector has been silenced temporarily.
   • It's time to perform a test.
   • The smoke detector is getting low on battery.
   • The smoke detector is dusty or clogged.
   • Smoke was previously detected.
2. 
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   Kidde smoke detectors have more red light alerts than First Alert. First Alert smoke detectors have more green light alerts. We've listed the most common red light alert reasons below. For more in-depth information, jump to our sections on Kidde smoke detectors or First Alert smoke detectors. If your detector brand isn't listed, the manual that came with the detector usually lists what each light pattern means. These manuals can also be found online.

   • Standby (Kidde only)
   • Alarm or test alarm
   • Alarm memory (Kidde only)
   • Hush mode/silenced alarm
   • Fault mode/malfunction detected
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   Leave the building and call for help if you're unsure if there's an emergency. If you can't figure out why your smoke detector is blinking red and you want to be sure there isn't an emergency, evacuate the building and call the fire department for help. If you aren't sure if there's an emergency, call the fire department's non-emergency line. Avoid calling 911 if possible unless you're certain there's an emergency.
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Section 2 of 4:

Kidde Smoke Detector Blinking Red

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   A blink once every 40 to 60 seconds means the detector is working normally. Depending on the model of smoke detector you have, a single flash of the red LED every 40 to 60 seconds means the detector is on standby mode and is functioning correctly.

   • In some models (such as some Kidde combination smoke/carbon monoxide detectors), the standby light will be green.
   • In other models, the red LED will flash every 60 seconds for the first 10 minutes after powering on or being reset. Then, it will flash just once every 10 minutes.
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   A rapid blink once per second means the alarm is going off. You should also hear the smoke detector making an alarm. In some models, the red LED will be flashing in the same pattern as the alarm pattern (if your smoke detector has multiple alarm patterns).

   • In an interconnected alarm system, only the smoke detector that detected the smoke or fire will be flashing red. Other alarms will make a sound but not have a blinking red light.
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   A 1.5-second long flash every 20 seconds is the detector's alarm memory. If you have an interconnected Kidde smoke alarm system, the alarms likely have alarm memory. This means that the alarm that detected the incident will indicate itself with a red flashing light so you know where exactly the smoke or fire was located.

   • To clear the alarm memory, press the Test button until the blinking goes away. It will also automatically clear after 11 to 24 hours (depending on the model of alarm you have).
   • If you have a combination smoke/CO detector, you may see a red light blinking every 15 seconds if the detector had detected smoke, and 2 blinks every 15 seconds if the detector had detected CO.
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   A 1.5-second long flash every 10 seconds indicates Hush mode. Hush mode will temporarily silence your smoke alarm. It's mostly used for nuisance alarms, like when your smoke alarm starts going off because it detected some smoke or steam from cooking. The alarm will stay in Hush mode for 10 minutes.

   • In some models of Kidde combination smoke/CO detectors, Hush mode is instead indicated by a red light blinking every 2 seconds.
5. 
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   Two to 12 flashes in 30 seconds along with chirping indicates fault mode. This means that something with the detector's electronics or sensors is faulty. The light will flash 2 to 12 times in 30 seconds, and the detector will chirp once every 30 seconds. If you notice this happening, contact Kidde's customer service department by calling 1-800-880-6788 for assistance.
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   The red light will blink in sync with various alarm patterns. These patterns vary slightly between device models, but in general, this is what each pattern means:

   • A blink and a chirp once every 30 seconds means your device has a low battery.
   • Two blinks and two chirps every 30 seconds means the device has reached its end of life and should be replaced.
   • If the test or Hush button is pressed, the red light will blink along with each alarm pattern. This only occurs if you manually press test/Hush.
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Section 3 of 4:

First Alert Smoke Detectors Blinking Red

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1. 
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   Three red flashes, a pause, and three more flashes indicate an alarm. The red LED will flash in sync with the beeps on your device. This also indicates an alarm test, but an alarm test will only occur if you press the test button on your smoke detector.

   • If you have an interconnected smoke alarm system, only the alarm that initiated the alert will blink red. The other alarms will blink green.
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   If the smoke alarm is silenced, the red LED will flash. Depending on your smoke detector model, the light might flash in different patterns (including the alarm pattern of 3 flashes, a pause, then three more flashes).
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   A flash once a minute with three rapid chirps indicates a malfunction. If the electronics or sensors inside your alarm have stopped working, you will see this flashing pattern. If this happens, contact First Alert's customer service for assistance by calling 1-800-323-9005.
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Section 4 of 4:

FAQ

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1. 1
   Why is my FireAngel smoke alarm blinking red? If you silence your FireAngel smoke alarm, it will blink red every 8 seconds until the 8-minute silent period ends.
2. 2
   Why is a red light flashing on my carbon monoxide alarm? On most carbon monoxide detectors, a flashing red light means that the battery or power source is working. If the red light stops flashing, you should replace the batteries.
3. 3
   How do I know if my smoke detector needs a new battery? If your smoke alarm starts emitting loud chirping sound every 30 seconds to one minute, that's usually a sign your battery needs to be replaced. Replacing the battery should make the smoke detector stop chirping.
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