Why Your Carbon Monoxide Detector Is Beeping

How to check it - and when it's okay to reset it

A woman pushes the test button to reset her beeping carbon monoxide detector.
​mikroman6 / Moment / Getty

Carbon monoxide is a colorless, odorless gas that can accumulate in closed spaces like your home or office. Since you can't smell or see carbon monoxide, you may suffer permanent damage, or even death, before you notice the onset of symptoms. When functioning correctly, carbon monoxide detectors alert you to the presence of this deadly gas in time to take life-saving action. But what if your carbon monoxide detector beeps for no apparent reason?

While it's essential to take any alarm from your carbon monoxide detector seriously, there are cases where it will beep or chirp in a non-emergency situation. Here are the most common reasons for a carbon monoxide detector to beep, and what to do when it happens.

Causes of Carbon Monoxide Detectors Beeping

When a carbon monoxide detector beeps or chirps at regular intervals, it's usually because of a battery problem or an internal fault or failure.

Here are the main things that can cause a carbon monoxide detector to beep:

  • Battery problems: When the battery condition drops below a set point, most carbon monoxide detectors will beep or chirp once every 30 seconds to one minute. If you have a plug-in carbon monoxide detector, the backup battery may be faulty or installed incorrectly.
  • Internal faults: When a carbon monoxide detector suffers from an internal defect, it will usually beep or chirp at regular intervals. Some units, including smart carbon monoxide detectors, can provide information about the issue.
  • End of life: Carbon monoxide detectors have a limited lifespan. When a unit reaches the end of its life, it will start beeping or chirping at regular intervals to let you know that it's time for a replacement. The frequency depends on the specific model, but it will typically beep more often than a detector that has a weak battery.
  • False alarm: Sometimes, a detector goes off even if there doesn't seem to be an issue with carbon monoxide. In this case, some troubleshooting is necessary before you reset the unit.

    A carbon monoxide detector that beeps or chirps at regular intervals cannot be trusted to alert you to the presence of carbon monoxide.

    Sources of Carbon Monoxide

    Carbon monoxide is usually produced in the home by fuel-burning devices, like furnaces, stoves, gas clothes dryers, and even fireplaces. Under normal circumstances, these devices release very little carbon monoxide, but that can change if they malfunction.

    There are also a handful of hazardous sources of carbon monoxide that you can avoid altogether. For example, you should never operate an outdoor grill or a propane heater indoors. Generators should also be operated a safe distance away from your home, as they create a lot of carbon monoxide during regular operation. Never run a generator inside your garage, even if the garage door is open.

    Cars are also a potentially dangerous source of carbon monoxide in the home. Never leave a car running in your garage, especially with the garage door closed. Like generators, even running a car near a window or door of your home can cause exhaust fumes to accumulate inside.

    Is it Safe to Reset a Carbon Monoxide Detector?

    Most carbon monoxide detectors are meant to be reset after an alarm (real or false), or after replacing the battery. Resetting a carbon monoxide detector is perfectly safe, as long as the device hasn't reached the end of its operational life. You must also first make sure that there isn't any carbon monoxide present.

    After a carbon monoxide detector sounds its warning alarm, it's crucial to identify and remove the source of carbon monoxide and ventilate the affected area. Emergency responders can check for carbon monoxide and determine whether any danger exists.

    How to Fix a Beeping Carbon Monoxide Detector

    If you've determined that there is not a dangerous buildup of carbon monoxide present, you'll have to track down exactly why the alarm went off.

    If your carbon monoxide detector sounds an alarm, don't take any chances. Press the test or reset button and then relocate everyone, including pets, to fresh air. Call emergency services, and wait for them to provide the all-clear before reentering the structure.

    Here are the steps to take if your carbon monoxide detector is beeping:

    1. Check the battery.

      Battery issues represent the most common cause of beeping carbon monoxide detectors. If the device is beeping or chirping at regular intervals, typically between about 30 seconds and one minute, it's probably because of a battery problem.

      Some carbon monoxide detectors come with a built-in sealed battery that's designed to last the life of the device. If you have one of these units, then you will have to replace it altogether when it dies.

      Other carbon monoxide detectors, including plug-in and hard-wired units that have backup batteries, come with replaceable ones. If you have one of these units, try replacing the batteries. You may also have to reset the device for it to stop beeping.

      Some carbon monoxide detectors include a battery light that will turn yellow or red when the battery is weak. Consult your owner's manual, or contact the manufacturer, for more information.

    2. Check for errors.

      When a carbon monoxide detector malfunctions, it may provide an error indication or message. Some units have an LED that lights up if an error is detected, and others have a display that will show a message like ERR or ERROR. Some units will also perform a double chirp every 30 seconds instead of a single chirp.

      You can usually retrieve error codes by pressing the test or peak level button, but you can't do much with one of these codes on your own. Carbon monoxide detector manufacturers require you to contact them with your error code to receive more information.

      Smart carbon monoxide detectors typically include a connected app that you can install on your smartphone. These apps sometimes allow you to view error messages, which can help narrow down the source of your problem.

      If you are sure that there's isn't a dangerous buildup of carbon monoxide present, try cleaning the inside of the detector with canned air or a vacuum. Then reset the unit.

      If the error comes back, verify that there isn't any source of carbon monoxide in your home, and then contact the manufacturer of the device for additional assistance. In most cases, you will have to replace the detector.

      Carbon monoxide detectors in this state are not capable of alerting you to the presence of carbon monoxide. Exercise extreme caution, as you will have no way to tell if carbon monoxide is present in your home until you fix the problem.

    3. Check the age of your detector.

      Carbon monoxide detectors are designed with a built-in shelf life because their internal sensors degrade over time. After a while, the sensor is no longer able to detect the presence of carbon monoxide adequately, and the detector is useless.

      If your carbon monoxide detector is beeping or chirping at regular intervals, even with a fresh battery, it may have ceased functioning.

      Some carbon monoxide detectors are designed to last up to 10 years. Check your owner's manual or contact the manufacturer if you think yours has failed early.

      If your carbon monoxide detector is beeping due to having reached the end of its operational life, the only fix is to replace it with a new unit.

      A carbon monoxide detector that has reached the end of its life will not sound an alarm if carbon monoxide builds up inside your home.

    4. Eliminate sources of false alarms.

      If your battery is fine, your detector doesn't indicate an error, and it's relatively new, then it might be a false alarm. In some cases, proximity to a gas-burning furnace or stove can cause issues.

      Try moving your carbon monoxide detector at least 15 feet away from these appliances, and see if that fixes the problem.

      If your gas-burning appliance isn't burning its fuel completely, it will create excessive amounts of carbon monoxide. If the pilot light has a yellow or orange flame, that's an indicator of incomplete combustion. To avoid carbon monoxide poisoning, you should have the appliance repaired or replaced as needed.

    5. Reset your carbon monoxide detector.

    Once you've ruled out a dangerous buildup of carbon monoxide, and gone through this list, you might have to reset the device.

    How to Reset a Carbon Monoxide Detector

    To reset a carbon monoxide detector, you must first connect it to a power source or install a fresh battery. In most cases, the reset process is automatic, so the goal is to silence the alarm while the detector resets itself.

    If the detector was exposed to carbon monoxide, then move it to an area with fresh air before resetting it.

    Here's what the reset procedure usually looks like:

    1. Locate the reset button.

      If your unit doesn't have a reset button, it might have one labeled test, test/silence, or something else. Consult your owner's manual, or contact the manufacturer if you are unable to locate the correct one.

    2. Push and hold the reset, test, or test/silence button for at least 10 seconds.

      Carbon monoxide detectors that are hard-wired or plug into a wall outlet must have power for the reset process to work. Make sure your device is plugged in, and that power is available.

    3. Release the reset button.

    4. If your device has successfully reset, it will typically beep or briefly illuminate an LED to show that it's working. Consult your owner's manual, or contact the manufacturer, for device-specific information.

    Smart Carbon Monoxide Detectors Beeping

    Smart carbon monoxide detectors are sometimes designed to provide you with more information than conventional ones when they experience a problem. These devices link to your smart home system through a smart home hub. Usually, they allow you to control the detector through an app on your smartphone.

    Smart carbon monoxide detector apps usually provide basic controls, like the ability to silence the alarm, which is useful during the reset procedure. Some of these apps are also designed to offer useful diagnostic information as well, which can help put you find out why your detector is beeping.

    Since smart carbon monoxide detectors are often designed to provide additional information through the connected app, make sure to check your app in addition to the steps outlined above. The problem is still likely to be a battery or end of life issue, but the app can help pinpoint the complication if you are experiencing another type of failure.