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What does a carbon monoxide detector sound like when it is going off?

A carbon monoxide detector sounding its alarm can be a scary experience. Carbon monoxide (CO) is an odorless, colorless gas that can be deadly if too much of it builds up in your home. Knowing what to listen for when your CO detector goes off could save your life.

When a CO detector detects high levels of carbon monoxide gas, it will make a very loud noise to alert you of the danger. Most carbon monoxide detectors make a repeating horn, beep, or chirp sound when they sense carbon monoxide in your home. This disturbing noise is designed to wake you up and prompt you to evacuate the building immediately.

In this article, we’ll go over exactly what carbon monoxide detector alarm sounds like, so you know what to listen for if your device ever goes off. We’ll also provide tips on where to install CO detectors, how to respond if one alarms, and how to keep your family safe from the silent killer.

What Does a Carbon Monoxide Detector Sound Like?

Carbon monoxide detectors are designed to emit very loud, high-pitched tones that are hard to ignore when they detect hazardous CO levels. Here are the main sounds you’ll hear from different CO alarm models:

Loud Beeping or Chirping

Most basic CO detectors emit a shrill “beep beep beep” or “chirp chirp chirp” alarm sound. This urgent beeping replicates the noise of a smoke detector, but faster and at a higher pitch. The beeps are spaced 1-2 seconds apart. This alarming sound is meant to alert occupants to the presence of carbon monoxide so you can get out quickly.

Repeating Horn or Siren

Some more advanced carbon monoxide detectors have a louder, more aggressive horn or siren sound when going off. This blaring alarm emits a repetitive horn wail, like a car horn or emergency vehicle siren. The deafening tone should wake up even the deepest sleepers and spur immediate action.

Voice Warning

A few high-tech “talking” CO detectors provide a verbal voice warning when they detect carbon monoxide. Once levels reach dangerous concentrations, the device will speak audible warnings like “Warning! Carbon monoxide! Leave immediately!” These voice alarms remove any ambiguity about what the sound means.

Combination Sounds

Some detectors combine beeping with voice warnings or alternating horn sounds to maximize noticeability. For example, a unit might first emit warning beeps, followed by a verbal “Carbon monoxide detected!” alert. This ensures the alarm fully awakens and alerts occupants in different ways.

Here is a quick video overview of the various sounds emitted by different CO detector models when going into alarm mode:

[Insert embedded video or link demonstrating CO detector alarm sounds]

As you can hear, all carbon monoxide alarms share a loud, grating sound that cannot be ignored or slept through. The noise will typically continue until you evacuate and the CO in the residence dissipates.

Where Should You Install Carbon Monoxide Detectors?

To ensure you can hear the alarm and react quickly if it sounds, install carbon monoxide detectors in optimal locations. Follow these recommendations:

– On every level of the home, including basements

– Near sleeping areas so the sound will wake you

– Within 15 feet of each bedroom door

– Avoid placing near windows, vents, or fans where air movement could disrupt CO sensing

– Follow all manufacturer instructions for ideal placement

Detectors are inexpensive and easy to find at hardware stores, online retailers, or home improvement centers. For maximum protection, install a combination smoke and CO alarm. Early alert to the presence of carbon monoxide or fire could save your household’s lives.

How to Respond to a Carbon Monoxide Detector Alarm

A blaring CO detector is a emergency situation requiring immediate action. Here are the proper steps to take if your carbon monoxide alarm ever sounds:

Evacuate the Building Immediately

As soon as you hear the CO detector’s alarm, exit the home with all occupants and pets right away. Do not waste time getting dressed, gathering belongings, or trying to investigate the source. Carbon monoxide can incapacitate and kill within minutes, so a swift evacuation is critical.

Call 911

Once safely outside, call 911 and report the sounding carbon monoxide detector to dispatchers. Explain where you are, that your CO alarm is going off, and request that emergency responders be sent immediately. Firefighters will arrive with equipment to locate the carbon monoxide source and ventilate the home.

Do Not Re-Enter the Home

Do not go back into the building for any reason until emergency crews have resolved the issue. Carbon monoxide can quickly overwhelm you with toxic fumes if you go back inside where concentrations are high. Wait until responders indicate it is safe before returning indoors.

Keep Your Family Safe from Carbon Monoxide

In addition to installing CO detectors and knowing how to respond if one alarms, there are further steps you can take to protect your loved ones from carbon monoxide poisoning:

Conduct Home Maintenance

Have furnaces, water heaters, chimneys, vents, and other features inspected annually by HVAC technicians to check for issues that could lead to CO buildup. Address any detected problems immediately. Install detectors near all combustion appliances.

Open Windows

Proper ventilation helps prevent carbon monoxide from accumulating. Open windows periodically, especially if burning fuels for heat or cooking.

Don’t Idle Vehicles in Garage

Avoid letting cars run indoors, even with the garage door open. Never operate gas-powered engines or charcoal grills inside an enclosed space.

Install CO Detectors

Check that you have working CO detectors on every level of the home and near sleeping areas. Replace batteries twice per year and units every 5-7 years. Newer models with electrochemical or infrared sensors have a longer lifespan than traditional detectors.

Know the Symptoms

Watch for signs of CO poisoning like headaches, dizziness, nausea, confusion, and flu-like effects. If you suspect exposure, evacuate and call 911 immediately. Medical attention can prevent lasting damage and death.


If you ever hear your carbon monoxide detector blaring its alarm, don’t take chances – get out fast! The loud, repetitive beeping, chirping, or horn sound means dangerous levels of CO are present and you must evacuate. Follow up by calling emergency services so firefighters can find and stop the source of the gas. Installing detectors properly, conducting home maintenance, and learning CO poisoning signs can also protect your family’s safety in the event of a silent CO leak. Recognizing the warning a CO alarm provides could save lives.

Type of Sound Description
Loud beeping or chirping Shrill, repetitive beeping similar to a smoke detector.
Horn or siren Blaring horn or siren sound, like a car alarm.
Voice warning Spoken audible alerts like “Warning! Carbon monoxide!”
Combination Mix of beeps, voice warnings, and siren sounds.
Location Reason
Every level of the home Detects CO no matter where it originates.
Near sleeping areas Alarm will wake sleeping occupants.
Within 15 feet of bedrooms Close enough to provide early warning.
Away from windows, vents, fans Prevents air currents disrupting sensing.
Response Step Purpose
Evacuate immediately Get out before CO can overwhelm you.
Call 911 Summons emergency help.
Don’t re-enter until safe Prevents prolonged CO exposure.
Prevention Method How It Helps
Home maintenance Fixes issues like leaks before CO builds up.
Open windows Ventilates and prevents CO accumulation.
Don’t idle vehicles indoors Prevents exhaust fumes from entering home.
Install CO detectors Provides warning if CO gas is present.
Know CO poisoning symptoms Allows early recognition and treatment.