Should my carbon monoxide detector be flashing green?

Author: Mr. Lucious Jerde  |  Last update: Thursday, December 4, 2025

A flashing green light is a normal part of the power up cycle. Any time there is a power outage, brownout, surge or other problem with the power, the alarm goes through a power up cycle. The flashing on your plug-in carbon monoxide alarm should stop after 5 minutes, then the light will stay a steady green.

Why is my carbon monoxide detector blinking green?

The green light will flash every 30 seconds indicating a CO reading is being taken and when any button is pressed. May be a breeze carried some smoke or carbon monoxide to the unit. Wait and see after 2 or 3 hours. If the issue exists after that also, there is some malfunction.

Is it normal for a carbon monoxide alarm to flash?

If the unit malfunctions, the red LED light will flash and the unit will chirp every 30 seconds indicating a system problem. If the red LED flashes every 60 seconds WITHOUT an audible chirp, this is the pre-warning that the battery will soon need replacing. The alarm is battery-operated with a 9V battery.

Should carbon monoxide detectors be on green lights?

Common CO Detector Indicator Lights and Their Meanings

Meaning: The LED lights blinks green per minutes usually indicates that the carbon monoxide detector is powered on and functioning correctly.

How to tell if a carbon monoxide detector is working?

How to test your carbon monoxide detectors to ensure they are working properly? To test your carbon monoxide detectors, press and hold the test button on the alarm. The detector will sound 4 beeps, a pause, then 4 beeps for 5-6 seconds. Refer to the user manual for your specific model.

Flashing green CO detector

Why is the green light blinking on my smoke detector?

When the detector senses a smoke or carbon monoxide hazard, the green light might become steady, whereas in “hush” mode, it may flash every 2 seconds. Alternatively, in other models, a flashing green light could simply denote that the detector is operating correctly and is in standard standby mode.

Why is the green light flashing on my Fireangel carbon monoxide alarm?

A continuous green flash indicates your CO alarm is activated and protecting your home. When low ambient light levels are detected at night time, the alarm will lower the light output.

How do I know if my carbon monoxide detector is expired?

CO alarm life span and end-of-life signal

CO alarms have a life expectancy of around 7 years. All CO alarms produced after August 1, 2009 have an end-of-life warning notification that alerts the resident that the alarm should be replaced. The CO alarm will beep every 30 seconds or display ERR or END.

What does green light mean on house alarm?

Typically, colored lights on your home alarm system often indicate similar messages such as: Solid or blinking green may indicate that your system is currently running without issue.

What color does a carbon monoxide alarm flash?

The CO Alarm has a distinctive on-off sound of 3 pulses, followed by a pause as compared with a typical Smoke Alarm which has a rapid pulsing sound. In addition, when your CO Alarm detects CO the red light will be flashing.

What if the carbon monoxide alarm goes off but no fire?

False or nuisance alarms are when your smoke detector or CO alarm goes off, but there is no presence of smoke or carbon monoxide in your home. However, if your smoke or carbon monoxide detector sounds indicating an emergency and you are not certain it is a nuisance alarm, evacuate the home and call 9-1-1.

Why is my smoke detector chirping but the light is green?

The battery may need to be replaced. An alarm will chirp every 30 to 60 seconds for a minimum of seven days. With a "low battery" announcement, disconnect the unit and replace the batteries. You can also put a unit into low battery hush for up to 12 hours on newer units by pressing the test/hush button.

Is it normal for carbon monoxide alarm to flash?

With all First Alert plug-in carbon monoxide alarms, any time there is a power outage, brownout, surge or other problem with the power, the alarm goes through a power up cycle. The flashing on your plug-in carbon monoxide alarm should stop after 5 minutes, then the light will stay a steady green.

What color does a CO detector change to when carbon monoxide fumes are present?

A reliable CO detector is an indicator tube which contains yellow silica is impregnated with a silico-molybdate compound. When air containing carbon monoxide is drawn through the tube the silica gel turns to a shade of green. Other types change from a tan color to gray or black.

How to tell if your carbon monoxide detector is faulty?

1 beep every minute: This means that the alarm has low batteries and you should replace them. 3 beeps every minute: This means the alarm has encountered a malfunction and needs replacement. 5 beeps every minute: This means your alarm has reached the end of its life and needs to be replaced with a new alarm.

How do I know when my carbon monoxide detector needs new batteries?

Smoke alarms alert you with three beeps in a row. Carbon monoxide alarms alert you with four beeps. A single chirp means the battery is low or the detector should be replaced.

How to tell if carbon monoxide is leaking?

What Are Signs of Carbon Monoxide in Your Home?
  1. Yellow or orange flames coming out of your gas appliances instead of the usual blue flame.
  2. Dark and sooty staining on or around gas appliances.
  3. Pilot lights that frequently blow out.
  4. Increased condensation on windows.
  5. Solid fuel fires burn much slower than usual.

Why is my carbon monoxide alarm blinking green?

A flashing green light is a normal part of the power up cycle. Any time there is a power outage, brownout, surge or other problem with the power, the alarm goes through a power up cycle. The flashing on your plug-in carbon monoxide alarm should stop after 5 minutes, then the light will stay a steady green.

Should green light be on carbon monoxide detector?

If the red or green light on your CO detector is illuminated, that's a sign that the unit has power. If the light is off, replace the batteries and follow the reset steps.

Why is my alarm flashing green?

… and the green light is constantly blinking, that means that the smoke alarm at some point went off, and the detector needs to be reset. The green light will remain blinking until you reset the alarm. First, try pressing the button on the front of the detector for five second.

Should the green light stay on for my smoke detector?

How to Tell If Your Smoke Alarm is Working. Hardwired units will have a steady green LED light to show that it's receiving AC power. Battery-operated units will have a quick flash every 30-45 seconds. This does not necessarily mean the alarm is working.

Previous article
Does WD-40 dissolve limescale?
Next article
Is dot and dab any good?