Solved! Why Is My Carbon Monoxide Detector Beeping?

Figuring out what your carbon monoxide detector is trying to tell you can be tricky. Here’s how to decode its beeps and chirps.
Tony Carrick Avatar
Pressing carbon monoxide detector button

We may earn revenue from the products available on this page and participate in affiliate programs. Learn More ›

Q: My carbon monoxide detector keeps beeping over and over again. How do I determine what the beeps mean?

A: Your carbon monoxide detector is beeping for one of three reasons: It’s detecting a dangerous level of carbon monoxide, alerting you to a low battery, or letting you know that it’s no longer functioning properly and needs to be replaced with a new unit. You can identify which of the three it is by decoding the pattern of beeps and chirps. Here’s how to speak your carbon monoxide detector’s language, and what you should do once you decipher its message.

First, understand how carbon monoxide detectors work.

Unlike smoke, which you can detect using your senses of sight and smell, carbon monoxide is completely invisible and has no odor, which is why it’s so dangerous.

According to the Environmental Protection Agency, the average home has a concentration of carbon monoxide of between 0.5 and 5 parts per million for homes without gas stoves and a concentration of 5 ppm to 15 ppm for those with gas stoves. Both of these levels are considered safe. Levels that linger above 70 ppm will start to cause headaches, fatigue, and nausea, eventually leading to unconsciousness and even death. The higher the concentration of carbon monoxide, the faster it can overwhelm those exposed to it.

A carbon monoxide detector protects you by sensing the concentration of this toxic gas in the air and sounding an alarm when levels are high for too long. How quickly carbon monoxide (or CO) will set off your detector depends on the concentration of the gas. A concentration of 70 to 80 ppm of CO will set off a carbon monoxide detector if those levels linger for about 2 hours, according to the National Institute of Standards and Technology. A much higher concentration of 400 ppm would set off the detector in a matter of minutes.

RELATED: Solved! What Does a Gas Leak Smell Like?

There are three common beeps to know.

Carbon monoxide alarm hanging on wall next to living room

A carbon monoxide detector communicates through a series of R2-D2-like beeps and chirps to let you know when it detects dangerous levels of carbon monoxide, when the battery is low, and when the unit is nearing the end of its life. Deciphering the pattern of beeps is crucial to understanding what your CO detector is trying to tell you, so you can make the right response. Here are the three common sounds you’ll hear:

  1. Single chirp. As with a smoke detector, a single intermittent chirp means that the battery in the carbon monoxide detector is low and needs to be changed. Stay safe and change the battery right away.
  2. Three beeps. If you hear the CO detector giving off three consecutive beeps every 15 minutes or four beeps every 5 minutes (depending on the manufacturer), then the CO detector is letting you know that it’s malfunctioning and needs to be replaced. Most CO detectors last about 5 years. Remove the old unit and install a new CO detector as soon as possible.
  3. Continuous alarm. When the carbon monoxide detector emits a continuous alarm or a set of four beeps in rapid succession, it has detected dangerous levels of carbon monoxide in the air. Exit the building and find fresh air immediately, then call 911 for help.

Keep in mind that the pattern of beeps, chirps, and alarms can vary from brand to brand, so consult the manufacturer’s instructions for details on interpreting your unit’s beeps.

After troubleshooting beeps, be sure to reset CO alarms.

Once the threat is over and the air quality in your home has returned to safe levels, you’ll need to reset the CO detector to put it back into service. Doing so will shut off the alarm and clear the carbon monoxide readings from the detector’s sensors so it can resume monitoring your home.

Look for the detector’s reset/test button on its faceplate. Press and hold the reset button for 5 to 10 seconds to turn off the alarm and reset the unit. Some CO detectors will reset themselves automatically after sounding for about 10 to 15 minutes.

If the CO detector alarm goes off after you’ve reset it, this means that CO levels are still high in your home. Evacuate to fresh air immediately and call 911 to help you find the source of the carbon monoxide.

It’s important to regularly inspect, test, and maintain carbon monoxide detectors.

Woman plugging in carbon monoxide alarm

Given how poisonous carbon monoxide is and how difficult it is to detect on your own, your carbon monoxide detector is among the most crucial pieces of safety equipment in your home, especially if you have gas-powered appliances. With that in mind, it’s critical that you test your carbon monoxide sensor about once a week. Hold down the test/reset button on the detector for about 5 seconds to test it. If it’s working properly, the unit should emit the same sound that it makes when it detects high carbon monoxide levels. If the detector fails to beep while you’re testing it, change the batteries and try again.

Along with testing your CO detector, keep it in good working order by wiping off any dust using a dry, soft cloth. Finally, don’t wait for your CO detector to let you know when the battery is low. Instead, change the battery every 6 months whether or not you hear your carbon monoxide detector chirping.

RELATED: Considering a Ventless Gas Fireplace? Here’s What You Need to Know

Proper installation can reduce false carbon monoxide alarms.

If your carbon monoxide detector is going off repeatedly and you’re certain there isn’t any carbon monoxide in the air, then it probably isn’t installed in the ideal location. Make sure your carbon monoxide detector is at least 15 feet away from any appliances that burn fossil fuels, such as gas furnaces and stoves. High humidity can also cause a CO detector to go off, so avoid installing them in bathrooms with showers or tubs.

Keep in mind that what you think is a false carbon monoxide alarm may be all too real. Check your gas-burning appliances to make sure they’re working properly. The pilot light and burner on these appliances should burn blue. Any yellow in the flame is a sign that the fuel isn’t burning completely, and this causes the appliance to create carbon monoxide. Turn off the burner and call your gas company’s gas leak hotline to help you fix the problem.