What to Do if a Carbon Monoxide Alarm Goes Off

What is Carbon Monoxide? 

Carbon monoxide (CO) is a colorless, odorless, non-irritating and tasteless gas produced by the incomplete combustion of carbon-containing fuels such as gasoline, wood, coal, natural gas, propane, oil, and methane. Common household sources of carbon monoxide include: 

• Clothes dryers 

• Water heaters 

• Furnaces or boilers 

• Fireplaces, both gas and wood burning 

• Gas stoves and ovens 

• Vehicles or generators running in attached garages 

• Grills, generators, power tools, lawn equipment 

• Wood stoves 

• Cigarette smoke 

• Natural gas, propane, kerosene, coal and gasoline 

What Causes Carbon Monoxide in a House Without Gas? 

What causes carbon monoxide in a house without gas can stem from several sources, even if you don’t use natural gas. Wood-burning stoves and fireplaces are common culprits, as incomplete combustion of wood can produce carbon monoxide, especially if chimneys or flues are clogged, preventing proper ventilation.  

Automobile exhaust is another major source carbon monoxide in a house without gas— running a car in an attached garage can cause carbon monoxide to seep into the home. Portable generators used indoors or too close to windows and doors can also lead to dangerous CO buildup. 

Similarly, charcoal grills should never be used indoors since burning charcoal emits CO, creating a serious health hazard and clogged chimneys or flues can cause carbon monoxide to backdraft into the house, making it difficult for the gas to escape. Improper ventilation is another factor — tightly sealed homes designed for energy efficiency may trap CO from various sources. Even malfunctioning appliances like furnaces, water heaters, or dryers that aren’t gas-powered can still produce CO if they burn fuel inefficiently.  

How Carbon Monoxide Detectors Work? 

CO detectors work around the clock, continuously scanning the air for carbon monoxide (CO) levels in parts per million (ppm) to detect even small traces of the gas. Since CO is odorless and colorless, these detectors serve as the first and only warning system against exposure. When CO levels reach a certain threshold, the detector sounds an audible alarm to alert occupants before dangerous exposure occurs. 

What Causes a Carbon Monoxide Alarm to Go Off? 

Many things cause a carbon monoxide alarm to go off. The most obvious causes of a carbon monoxide alarm going off is the actual presence of carbon monoxide. Dangerous levels resulting from sources like faulty appliances or idling vehicles can cause this device to sound off.  

In the same way, devices such as furnaces, water heaters, or stoves that are not operating correctly can emit CO if they are not operating correctly or are poorly ventilated. Obstructions in front of gas appliances like furniture, plants, walls can prevent carbon monoxide from venting outdoors, causing it to accumulate indoors. This can cause a carbon monoxide alarm to go off with this excessive build up. 

Even with open garage doors, idling cars can produce CO that seeps into the home. Over time, this buildup can reach dangerous levels, especially in attached garages or poorly ventilated spaces, posing a serious health risk to occupants. This build-up causes a carbon monoxide alarm to go off. Lastly, using charcoal grills, portable gas stoves, or generators inside or near open windows can lead to dangerous CO buildup causing alarms to go off.   

False Alarms That Cause a Carbon Monoxide Alarm to Go Off 

Carbon monoxide alarms do go off because of false alarms. Some detectors emit warning chirps when batteries are low, which can be different from the alarm sound for CO detection. Enviromental factors like high humidity, steam, or proximity to chemicals can sometimes trigger false readings too. Lastly, carbon monoxide alarms have a limited lifespan of 5-7 years and may alert you when they need replacement. 

What to Do If a Carbon Monoxide Alarm Goes Off 

When your carbon monoxide alarm goes off, every second counts. Whether it’s a real emergency or a false alarm, taking the right steps can save lives. Here’s exactly what to do if your carbon monoxide alarm goes off: 

Step 1: Do Not Ignore the Alarm—Assume It’s Real 

The first step in what to do if your carbon monoxide alarm goes off is to not take the alarm lightly. Carbon monoxide is invisible and odorless—you won’t be able to detect it yourself; your alarm will.  

Carbon monoxide exposure can lead to sickness and long-term illness if not treated right away. Even if no one is feeling sick, CO exposure can be gradual, and early symptoms like headaches and dizziness are often ignored. If the alarm sounds continuously (not just an occasional chirp), take immediate action. 

Step 2: Evacuate Immediately—Get Everyone Out 

Do NOT waste time trying to open windows or shut off appliances—your top priority is to get out of the house quickly. Help children, elderly family members, and pets exit as fast as possible. If you can, leave doors open on your way out to allow fresh air to circulate and help reduce carbon monoxide levels.  

If someone collapses inside, do NOT go back in—wait for emergency responders to arrive to help them. Fast action is critical when it comes to what to do if your carbon monoxide alarm goes off to prevent serious harm.  

Step 3: Call 911 or Emergency Services 

Once you’re safely outside, call 911 or your local fire department. Emergency responders have the proper equipment to measure carbon monoxide levels and determine if it’s safe to return.  

If you rent your home, notify your landlord immediately so they can take appropriate action. Emergency services will investigate the source of the carbon monoxide and make sure your home is safe before you go back inside.  

Step 4: Do NOT Re-Enter Until Authorities Confirm Safety 

Carbon monoxide can linger in the air, even if you’ve aired out the house. If your alarm stops doesn’t mean it’s safe to return. Wait until firefighters, emergency responders, or a gas technician confirm that CO levels have returned to normal and the source of the leak has been identified.  

If authorities advise you to stay out overnight, arrange for temporary shelter with friends, family, or local emergency services. Safety should always come first when handling what to do if your carbon monoxide alarm goes off. 

Step 5: Identify and Fix the Source Before Returning 

Before turning any appliances back on, have all fuel-burning systems inspected by a licensed HVAC technician or utility provider. This includes furnaces, water heaters, fireplaces, and stoves, as well as any clogged chimneys or blocked vents.  

If the alarm was triggered by a false alarm, clean or replace the detector as needed. In some cases, carbon monoxide can enter the home through vehicle exhaust from an attached garage, so have any potential garage or car-related leaks checked as well.  

What Does a Carbon Monoxide Alarm Sound Like? 

Understanding what does a carbon monoxide alarm sound like is essential for recognizing the difference between a maintenance issue and a life-threatening emergency. Carbon monoxide  alarms produce different beeping patterns, each with a specific meaning. Here’s what those different sounds mean: 

Regular Beeps – Malfunction Alert 

If your CO detector beeps three times in a row every five minutes, it indicates a malfunction or that the unit needs to be replaced. Some newer models have voice alerts or LED indicators to provide more detailed information about the issue, so check your user manual for guidance. If the beeping continues after you’ve replaced the battery and reset the unit, it’s time to replace the detector. 

Knowing what does a carbon monoxide alarm sound like when it’s malfunctioning can prevent false alarms and ensure your detector is functioning properly when it matters most. 

Consistent Chirping Every 30 Seconds – End of Life Warning 

If your CO detector chirps every 30 seconds, it’s most likely not a carbon monoxide emergency but rather an indication that the alarm is nearing the end of its lifespan which typically lasts around 7 years. 

In this case, replacing the battery won’t stop the beeping—you’ll need to replace the entire detector. For plug-in models, this sound could also indicate that the backup battery is loose or not connected correctly. 

Single Chirp Every 60 Seconds – Low Battery or Carbon Monoxide Presence 

A single chirp every 60 seconds typically signals a low battery. Try replacing the battery and see if the chirping stops. However, if the beeping pattern changes to multiple beeps every few seconds, this could indicate dangerous CO levels. In that case, evacuate immediately and call emergency services. 

Continuous Four Beeps: A Critical Warning 

Four continuous beeps signal an emergency—your home has reached dangerously high carbon monoxide levels. This is the most serious alarm pattern and requires immediate action. Evacuate the home right away, help children and elderly family members exit safely, and leave doors open to allow fresh air in. Call 911 or your local fire department once you’re outside. 

Recognizing what does a carbon monoxide alarm sound like and responding appropriately to each type of alert ensures that you can act quickly in an emergency with the right information. 

How to Turn Off a Carbon Monoxide Alarm 

Knowing how to turn off a carbon monoxide alarm is important, so you know how to avoid false alarms and ensure the detector is functioning properly when a real emergency occurs.  

Before turning off, a carbon monoxide alarm, you need to confirm that there is no immediate danger. Before silencing the alarm, be sure to evacuate everyone from the home and move to fresh air to ensure everyone’s safety before you start. 

To turn off a carbon monoxide alarm follow these steps: 

1. Silence the Alarm: Most CO detectors have a ‘silence’ or ‘reset’ button Press and hold this button for about 10 seconds to temporarily stop the alarm. Some models may have different reset methods, so check your user manual if the alarm doesn’t respond. 
2. Ventilate the Area: Open windows and doors to allow fresh air to circulate. Even if no carbon monoxide leak is detected, ventilating the space helps clear out any lingering gases just in case and improves air quality. 
3. Identify and Address the Source: If the alarm was triggered by an actual CO leak, have a qualified technician inspect and repair potential sources such as furnaces, water heaters, gas stoves, and fireplaces. If no source is found, it’s possible that environmental factors, like a running car in the garage, caused the alarm. 
4. Rest the Detector: After the environment is confirmed to be safe and any issues have been resolved, press the reset button on the detector to resume normal operation. If the alarm continues to sound after resetting, replace the unit—it could be faulty or at the end of its lifespan. 
5. Replace Batteries or the Unit if Necessary: If the alarm beeps intermittently after resetting, it may be signaling a low battery or that the unit needs to be replaced. Fo plug-in models, ensure the backup battery is properly installed.  

Risks of Carbon Monoxide Poisoning 

Gas appliances, such as stoves, furnaces, and water heaters, can produce carbon monoxide if not properly ventilated or maintained and you can risk subjecting yourself to carbon monoxide poisoning. Some noticeable symptoms of carbon monoxide poising include 

• Headache 

• Dizziness 

• Fatigue 

• Nausea and vomiting 

• Confusion or loss of consciousness and more if not treated.  

Severe exposure can lead to brain damage or death if not addressed promptly. Installing carbon monoxide detectors in your home, especially near sleeping areas and gas appliances, is crucial for safety. If you experience symptoms and suspect CO exposure, leave the area immediately and seek medical help immediately. 

What Should I Do if I Suspect CO Poisoning?  

Act fast—carbon monoxide poisoning can be deadly. If you or someone else is experiencing symptoms like headache, dizziness, nausea, confusion, or weakness, follow these steps immediately: 

1. Get to fresh air immediately. Leave the building and move to an open space where you can breathe clean air. 
2. Call 911 right away. Even if symptoms seem mild, carbon monoxide exposure can worsen quickly, leading to unconsciousness or death. 
3. If possible, shut off potential carbon monoxide sources. Turn off fuel-burning appliances (stoves, furnaces, or generators) if you can do so safely. 
4. Leave doors and windows open. This allows fresh air to circulate and helps reduce CO buildup inside the home. 
5. Contact the fire department. They can test carbon monoxide levels and confirm whether your home is safe to re-enter. 
6. Do NOT assume you’re safe just because you feel better outside. Carbon monoxide poisoning symptoms can return once you’re back inside if carbon monoxide is still present. 
7. Seek medical attention if needed. carbon monoxide exposure can cause lasting damage, so even if symptoms subside, get checked by a doctor. 

Types of Carbon Monoxide Sensors 

Choosing the right carbon monoxide (CO) sensor depends on your home setup, lifestyle, and level of protection needed. Here’s a breakdown of the different types and which homeowners will benefit most from each: 

Electrochemical Sensors – Best for Most Homes & Apartments 

Electrochemical sensors use a gel to detect carbon monoxide and is mainly used to detect oxygen and toxic gas. The higher the CO levels, the stronger the current, triggering the alarm. 

This alarm is most reliable for residential use—used in most modern CO detectors.
Minimal false alarms—includes hydrogen sulfide filters to reduce interference.
Best for homes with gas appliances—accurately detects even low levels of CO from furnaces, stoves, and fireplaces. 

This sensor is ideal for those families and individuals who want a dependable, low-maintenance CO alarm with strong accuracy. 

Biomimetic Sensors – Best for Low-Maintenance Homes & Vacation Properties 

A biomimetic sensor darkens when exposed to CO, mimicking how the human body reacts to carbon monoxide. The sensor detects this color change and triggers the alarm. Biominetic sensors are low maintenance and don’t require electricity or constant recalibration. This device is highly reliable for homeowners who don’t want to test or replace batteries frequently. Biomimetic sensor are good for vacation homes—functions well in places that aren’t occupied year-round. 

Semiconductor Sensors – Best for Homes with Fast-Detection Needs 

Semiconductor sensors use a metal oxide semiconductor (MOS) that reacts to CO by altering its electrical resistance, quickly setting off the alarm. A metal oxide semiconductor (MOS) is a type of electronic switch that turns on or off based on voltage. It helps control signals and is often used for amplifying or switching electrical currents in devices. 

This device is fast-acting—and reacts more quickly than other sensor types, providing early warning. This device is great for homes with attached garages—where CO exposure from vehicles can be sudden and dangerous and good for homes with high gas usage—detects even small CO leaks from stoves, furnaces, and water heaters. 

Where to Place Carbon Monoxide Alarms 

Proper placement of carbon monoxide (CO) detectors is essential for early detection and safety. Here where to position your carbon monoxide alarm: 

1. Install and position your carbon monoxide alarm outside each bedroom to ensure everyone is alerted if CO levels rise at night. 
2. Vehicles left running can produce dangerous carbon monoxide levels, so having a detector in the garage helps catch leaks early. 
3. Be sure to place a carbon monoxide alarm on every level of the home, including the basement – carbon monoxide can spread throughout the house, so having a detector on each floor provides complete coverage. 
4. Place a carbon monoxide alarm at least 10 feet from the garage entrance to your home – carbon monoxide from vehicles can enter through doors in your garage, so placing a detector nearby (and in rooms above the garage) adds an extra layer of protection. 
5. Position a carbon monoxide alarm At least 15 feet away from gas-burning appliances – Items like fireplaces, stoves, and furnaces naturally emit small amounts of CO, which can trigger false alarms if detectors are placed too close. 
6. Avoid placing carbon monoxide alarms too close to fireplaces or stoves since natural carbon monoxide emissions may cause unnecessary alarms.  
7. Keep them away from humid areas like kitchens and bathrooms as moisture can affect sensor accuracy.  
8. Avoid positioning a carbon monoxide alarm near open windows or direct sunlight, as environmental factors like drafts and heat may impact readings.  
9. For new homes, use interconnected CO detectors so that when one alarm sounds, all alarms go off—check local building codes for specific requirements. 
10. If you’re installing only one CO detector, place it near sleeping areas and ensure its loud enough to wake everyone in the home. 

Test a Carbon Monoxide Detector with Candle – Myth or Fact? 

There’s a common belief that you can test a carbon monoxide (CO) detector by holding a candle near it. But is this a reliable method? 

Myth: Holding a candle near a CO detector can test its functionality. 

Fact: This method is unreliable and can damage the detector. 

This method doesn’t work because carbon monoxide detectors use specific sensor technology to detect CO in parts per million (ppm). The heat and smoke from a candle do not produce carbon monoxide in measurable amounts, so holding a candle near the detector won’t trigger a response or confirm whether the unit is working properly. 

CO detectors rely on electrochemical, biomimetic, or semiconductor sensors. While smoke detectors respond to particles in the air, CO detectors respond only to CO gas. Introducing smoke particles near the detector can clog or coat the sensor, causing false alarms or reducing sensitivity over time. 

 Holding an open flame too close to the detector may cause internal components to overheat. Heat damage can impair the detector’s ability to accurately detect CO levels or shorten its overall lifespan. Some CO detectors are designed to withstand minor environmental changes, but direct exposure to high heat can cause permanent malfunction. 

Does Carbon Monoxide Smell Like Rotten Eggs? 

 Carbon monoxide does not smell like rotten eggs. Carbon monoxide has no smell, color, or taste. This makes it impossible to detect without a carbon monoxide detector, making it one of the leading causes of accidental poisoning in homes. Because people cannot see, smell, or taste CO, they may inhale dangerous levels without any warning—often while sleeping or unaware. 

Unlike natural gas, carbon monoxide is not odorized. Utility companies add a sulfur-like “rotten egg” smell to natural gas for leak detection, but carbon monoxide has no such warning sign.  

If you smell rotten eggs, it’s NOT carbon monoxide—it’s likely a natural gas leak. Leave the area immediately and call your gas provider or emergency services. 

Seasonal Carbon Monoxide Safety: Preventing Carbon Monoxide Risks Year-Round 

Carbon monoxide dangers aren’t limited to winter—each season comes with its own risks. Whether you’re heating your home in the winter, using a generator during summer storms, or grilling outdoors, it’s important to understand how seasonal activities can increase carbon monoxide exposure and how to protect your household. 

Winter Risks: Increased Carbon Monoxide Exposure Indoors 

1. Heavy Use of Heating Appliances – Gas furnaces, space heaters, fireplaces, and wood stoves run more frequently in cold months, increasing the risk of carbon monoxide leaks. Ensure regular maintenance and proper ventilation. 
2. Blocked Chimneys and Vents – Snow and ice can clog vents, preventing carbon monoxide from escaping and causing it to build up indoors. Check for obstructions after storms. 
3. Car Exhaust in Garages – Idling a car in an attached garage, even with the door open, can be fatal. Always move the car outside before warming it up. 
4. Power Outages & Generator Use – Winter storms can lead to increased generator usage, and running one too close to the home can cause carbon monoxide poisoning. Place generators at least 20 feet away from doors and windows.  

Summer Risks: Unexpected Carbon Monoxide Dangers 

1. Portable Generators During Power Outages – Severe weather, hurricanes, and heatwaves often cause power failures, leading to increased use of gas-powered generators. These should always be kept outdoors, at least 20 feet from the home with exhaust directed away from living areas. 
2. Boat Engine Exhaust & RVs – carbon monoxide poisoning is common on boats and recreational vehicles, especially when docked or running a motor in an enclosed space. Ensure proper ventilation and install carbon monoxide detectors in cabins and RVs. 
3. Gas Grills and Outdoor Appliances – Propane grills, patio heaters, and outdoor fireplaces produce CO and should never be used in enclosed spaces like tents, garages, or screened porches. 
4. Cooling System Malfunctions – Some faulty air conditioning and ventilation systems can lead to improper airflow, potentially causing CO buildup indoors. 

FAQs  

Do carbon monoxide alarms expire? 

Yes, carbon monoxide alarms expire after 5-7 years, depending on the manufacturer. Most modern detectors will beep periodically when they need replacement. 

Can Pets Be Affected by CO Poisoning? 

Yes, pets are susceptible to carbon monoxide poisoning and may exhibit symptoms like lethargy, vomiting, or coordination issues. If your pet shows these signs, seek veterinary care immediately. 

Is It safe to ignore a carbon monoxide alarm if no one shows symptoms of carbon monoxide poisoning? 

You should never ignore a carbon monoxide alarm. Carbon monoxide exposure can affect individuals differently, and symptoms might not be immediately apparent. Always evacuate and contact emergency services if an alarm sounds. 

How does weather conditions affect CO buildup in homes? 

Cold weather can lead to tightly sealed homes, reducing ventilation and increasing the risk of CO accumulation from heating sources. Ensure proper ventilation and regular maintenance of appliances, especially during winter months. 

Are some people more sensitive to the effects of carbon monoxide?  

Carbon monoxide can impact individuals differently based on their age and overall health. Even at low levels, elderly individuals, infants, pregnant women, people with anemia, and those with heart or respiratory conditions may be more vulnerable to its effects. 

Should I worry if my carbon monoxide alarm goes off? 

Yes, take it seriously. A carbon monoxide alarm means there may be dangerous CO levels in your home. Evacuate immediately, get to fresh air, and call emergency services to assess the situation. Never ignore the alarm, even if no one is showing symptoms. 

Protecting your home and loved ones from carbon monoxide dangers starts with awareness, proper CO detector placement, and regular maintenance. By ensuring your CO alarms are functional and responding promptly to any alerts, you’re taking a proactive step toward home safety. 

Just like taking steps to safeguard your home with a reliable CO detector, having a trusted energy supplier helps you maintain peace of mind in other areas of your home. At Santanna Energy Services, our energy plans are designed to provide fixed-rate stability and cost predictability—making sure that you can focus on what matters most, without unexpected surprises. 

Safety and peace of mind go hand in hand, whether it’s protecting your home from carbon monoxide or ensuring your energy needs are met with confidence. Explore our energy plans today and find the right fit for your lifestyle.