Carbon Monoxide Alarm Going Off (What To Do Next?)

Many people panic when they hear their carbon monoxide alarm going off. Carbon monoxide is incredibly dangerous as it is a silent killer. How do you deal with it and ensure that you prevent yourself and your loved ones from getting carbon monoxide poisoning?

When your carbon monoxide alarm goes off, the most reasonable thing to do is get out of the house and call emergency services. Let them know what your symptoms are when they arrive. If the alarm stops beeping, ventilate your house, switch off all fuel-burning appliances, and reset your alarm.

Do not ignore the alarm or remove batteries from the carbon monoxide detector (without resolving the issue), as you could be getting poisoned and putting your life in danger.

Carbon Monoxide Alarm Going Off

What Is Carbon Monoxide And What Makes It Dangerous?

Carbon monoxide is an alarmingly dangerous gas that can kill you as it is poisonous. It is so dangerous that it is hard for humans to detect if they do not have any carbon monoxide alarm installed in their home because you cannot smell it, see it, or taste it.

Elders and small children are more at risk of carbon monoxide as they tend to be more fragile and open to poisoning than young adults. Carbon monoxide comes from any fuel-burning appliances that many people have in their homes. For example, it can come from wood stoves, gas appliances, power generators, hot water heaters, and charcoal grills.


Why Does Your Carbon Monoxide Alarm Keep Going Off?

I’m so sorry to hear that your carbon monoxide alarm is going off. I can totally understand how upsetting this must be.

Carbon monoxide (CO) poisoning is a serious matter and should be taken seriously. If you have an alarm that goes off when carbon monoxide is detected in your home, it’s an indication that the alarm needs to be addressed. You won’t always know the cause of your CO alarm going off, so how would you be able to address it. 

The most common reason for a carbon monoxide alarm going off is because it’s doing its job—that’s the good news. That means that, yes, there is carbon monoxide in your home. Usually, it’s coming from a malfunctioning appliance or a flue that needs to be adjusted or repaired. 

One of the other typical reasons your carbon monoxide alarm is going off is your car. When you start your car, usually in the garage, the carbon monoxide is transferred into your living areas via the garage door, which leads to copious amounts of car exhaust setting off the alarm.

Here are some of the most common reasons why your CO alarm might be going off:

  1. Your carbon monoxide detector is doing its job and detecting CO pollution in the air. This may be because of a gas leak or improper venting inside your home.
  2. Your carbon monoxide detector had a false alarm due to other household items such as smoke from cooking, indoor grills, or even scented candles. This is actually very common for CO detectors and is nothing to worry about. Please check your detector’s manual for more information on resetting the alarm after setting off a false alarm.
  3. Your carbon monoxide detector might be malfunctioning or needs new batteries. We recommend having your CO detector checked by a professional if it continues to set off false alarms.


What Should You Do When The Carbon Monoxide Alarm Goes Off?

The first thing that you need to know is what the carbon monoxide alarm sounds like. Once you have identified that it is the carbon monoxide alarm going off, the first thing to do is check on the people living with you inside the house if you do not live alone.

If no one, including yourself, is not exhibiting any of the carbon monoxide poisoning symptoms, you should immediately open your windows and doors to air out the house, turn off any fuel-burning appliances, and reset your carbon monoxide alarm. After you have done all this and your carbon monoxide alarm goes off again, call the fire department.

If you or the people in your home have carbon monoxide poisoning symptoms when you check on them and the alarm keeps on going, instead of emitting a test noise, then you need to immediately get out of the house.

As much as you want to take the time to air out the house, don’t. The chances of you passing out on the spot and getting overwhelmed by carbon monoxide are very high. As soon as you exit your house, call emergency services, like 911.

Ensure that you remain out of the house while you wait for the fire department to arrive and measure the carbon monoxide levels in your home. Inform the fire department and EMTs of the symptoms you are having, if any.

If you have a chimney, this is the perfect time to call a certified chimney professional and an HVAC contractor so that they can check and make sure that all of your gas appliances are in perfect working condition and that they are getting vented out of your home through the chimney most effectively and efficiently.

Paste the user guide somewhere where everyone can see it or keep it in a place where it can be accessed fast. This way, if you are not quite sure what to do or your mind goes blank when you panic, you can simply follow the emergency procedures outlined in the user guide.


Carbon Monoxide Alarm Signals To Lookout For

Here is a general guide on what each alarm signal and warning means.

What is the carbon monoxide alarm signal under normal conditions?

Under normal conditions, when there is no carbon monoxide present, the green LED on your carbon monoxide alarm will flash once every thirty seconds, depending on the model that you have. This is a clear indication that the alarm is powered and is operating well.


How do you know when to replace the batteries of your alarm?

If the alarm’s batteries need to be replaced, the alarm will usually beep or chirp for 60 seconds, and again, the red LED will flash at the same time. The interval depends on your carbon monoxide detector, as this is a general guide.


How can you tell when your carbon monoxide alarm has reached the end of its life?

When your carbon monoxide alarm reaches the end of its life, it will beep twice in quick succession every 30 seconds, and the red LED will flash simultaneously. Replace the entire alarm when this happens.


What to do when malfunctions happen with your alarm?

If a fault or malfunction happens with the alarm, it will chirp once every 30 seconds, and the red LED light will flash too. Immediately replace the alarm if this happens.

Alternatively, malfunctions will lead to the alarm emitting a loud continuous sound together with the flash of the red LED. Contact the customer services of your model if this happens.


Can carbon monoxide alarms go off for no reason?

Yes, carbon monoxide alarms do go off for no reason sometimes, but only if the unit is not maintained well as per the manufacturer’s instructions or because of a defect in the detector.

When properly maintained, carbon monoxide alarms are equipped to provide early warning signs of a potentially dangerous situation. If you find that your alarm is going off excessively or unnecessarily, check the owner’s manual and make sure that you have cleaned out the unit as recommended and changed the batteries as needed.

If the alarm still goes off for no reason, it means there might be a problem with the unit itself and you should get it replaced. 


What happens when dangerous levels of carbon monoxide levels are detected?

If high levels of carbon monoxide levels are detected, the alarm will emit four quick beeps followed by a five-second pause. This will continue while dangerous carbon monoxide levels are being detected. Follow emergency protocol.


What is the benefit of having an LCD digital screen alarm?

If your alarm has an LCD digital screen, to detect dangerous levels of carbon monoxide, look at the screen as the numbers will be displayed on the screen along with the four quick beeps. If the levels are normal, the LCD screen will display a zero.

What makes alarms with an LCD screen appealing is a peak level display feature that reveals the highest level of carbon monoxide detected since the alarm was last reset. This helps alert you that carbon monoxide has been present in your home and that it is time to get your appliances checked.

The LCD digital screen will also display Lb for a low battery or EOL for end-of-life.

For all of the above, check your carbon monoxide user guide as the alarm signals and warnings can vary between different models.


What Are Symptoms Of Carbon Monoxide Poisoning?

Now that you are aware of what you need to do when your carbon monoxide alarm goes off, here are some symptoms that you should be on the lookout for so you can mention them to the EMTs or, better yet, immediately go to the hospital.

Symptoms of carbon monoxide poisoning are often: extreme fatigue, chest pains, confusion, dizziness, vomiting, headaches, nausea, and flu-like symptoms. Ensure that you get treated as soon as possible, as carbon monoxide poisoning can lead to death if not treated.


How Can You Detect And Stay Safe From Carbon Monoxide?

There are several ways you can be proactive to keep your family safe from carbon monoxide poisoning.

Ensure That You Have Carbon Monoxide Alarms In Your Home

Always install a carbon monoxide alarm in your home, preferably near your bedroom, especially if you have any fuel-burning appliances. Carbon monoxide alarms are made to alert you if carbon monoxide is present in your home.

This ensures that your family is kept safe and sound. Some states like Washington require all rental apartments and homes to have carbon monoxide alarms installed in their homes. Check with your landlord as they are responsible for providing those alarms.


Avoid Using Fuel Burning Appliances Inside Your Home

Although fuel-burning appliances like gas and charcoal grills may be convenient, the carbon monoxide produced by them can reach dangerous levels when used inside your home or garage.

Yes, you may think that it might not be a big deal if you use them while your windows and doors are open, but the truth is, that will not be effective in keeping the carbon monoxide levels low.


Always Uninstall Expired Carbon Monoxide Alarms

Often we become lazy or completely forget to check the expiry dates of certain devices. A carbon monoxide alarm is something that you should always check. Be aware of when a carbon monoxide alarm expires. One way to determine if you forget is when the carbon monoxide alarm installed keeps beeping every 30 seconds.

This means that your carbon monoxide alarm has expired and needs to be replaced as soon as possible. I’ll be the first to admit that I’m not a fan of spending money to replace devices, but in this case, it is imperative as carbon monoxide alarms are only manufactured to last around seven years.

Although your fingers may itch to dial 911 when your alarm keeps keeping every 30 seconds, don’t, all you need to do is replace the alarm. Replacing just the battery will not do the trick. You need to replace the entire alarm system.


Get A Battery Powered Backup Carbon Monoxide Alarm

If you are using a carbon monoxide powered from an outlet, get a battery-powered carbon monoxide alarm as a backup. Sometimes, the electricity can temporarily go off during storms, etc., and you will be left unprotected.


Where Should Carbon Monoxide Alarms Be Placed At Home?

For carbon monoxide alarms, it is wise to have one on each level of your house, basement included, and one in the hallways that lead to the sleeping areas of the house.

It is recommended to have different brands because sometimes, carbon monoxide alarms do not go off as soon as they should.

From a detector test, only 3 out of 10 carbon monoxide detectors met the standard, which is to sound within 15 minutes of when carbon monoxide levels reach 400 parts per million.

Some went as high as 1000 parts per million without emitting emergency beeps, which is high enough to kill people within an hour. Others did not even get activated, so they never went off at all.


How To Detect Carbon Monoxide If The Alarm Does Not Go Off?

Your carbon monoxide alarms will not go off unless your carbon oxyhemoglobin levels are likely above 10%. This means that you have more than 10% carbon monoxide in your blood, which is a dangerous level. Nearly half the people that get 10 % are at risk of getting brain damaged.

When they designed carbon monoxide alarms, they were too conservative because they did not want many false alarms. The first sign that you have carbon monoxide, but the alarm is not alerting you, is people do not all get the same flu-like symptoms directly at the exact same time.

If it is within minutes of each other, it is an environmental problem and not an illness problem. Immediately get out of the house, office, or wherever you are indoors and call 911 even if the carbon monoxide alarm is not going off.


All About Carbon Monoxide Brain Damage

Most people recover from carbon monoxide poisoning once they get away from the gas. However, exposure can cause brain injury. The symptoms of carbon monoxide poisoning leading to brain injury are similar to those people get from other brain injury causes.

These might include decreased balance, headaches, vision difficulties, dizziness, sleep problems, cognitive or thinking difficulties, especially with short-term memories, processing speed, mood problems, executive functioning, and difficulty with movements.

Although you may feel fine, be on the lookout as these symptoms can reveal themselves a few days after exposure, or maybe even a few weeks or months after the exposure.

Carbon monoxide causes injury to the brain in several different ways, such as preventing the brain cells from getting enough oxygen, binding to red blood cells so they cannot carry enough oxygen, which leads to the cells getting injured or dying, your energy production is decreased, and there can be a breakdown of protein with some of the nerves around the brain.



We hope you’ve found these tips helpful, whether you’re a landlord, a tenant, or someone who just wants to make sure they’re doing things right.

It’s important to be prepared when it comes to home safety. Plans as simple as a fire escape plan, or as complicated as knowing what to do if your carbon monoxide detector goes off, can keep you safe in an emergency. If you have children or others who may need extra care during an emergency, be sure they know what to do.

Please make sure you follow our guidelines for what to do if your carbon monoxide detector goes off so that you can be sure to take all the right precautions when your life depends on it.

And don’t forget to spread the word—there is a lot of misinformation about this subject online, and we want everyone to have clear facts so they can be safe.

Thanks again for reading!

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Edward Clark
Edward Clark, with 15 years of hands-on experience, is a distinguished expert in smart locks and home security systems. He holds a B.S. in Computer Engineering with a focus on Cybersecurity and is a member of the Electronic Security Association (ESA). His credentials include certifications from ASIS International, IAPP, CompTIA, NTS, and CEDIA. With expertise spanning risk management, electronic security, and data privacy, he's been featured in The Guardian, Forbes, Wired, and more. Edward's mission: guiding individuals toward secure homes using the latest technologies.

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