co alarm goes off

Carbon monoxide expert , we have been engaged in the field of security for more than ten years. Now we will share experience and personal opinions with readers by writing articles, hoping to help readers.

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Why is your carbon monoxide detector beeps and how to deal with it

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Carbon monoxide, also known as CO, is a colorless, odorless gas that is produced when fossil fuels such as wood, coal, charcoal, gasoline, kerosene, natural gas, or oil are incompletely burned. Because it is not easy to detect and is very harmful to the human body, it is easy for people to die in their sleep, so it is also known as the silent killer.

1.How long does it take to get carbon monoxide poisoning

The poisoning time of carbon monoxide mainly depends on the concentration of carbon monoxide in the current environment. The higher the concentration of carbon monoxide, the faster the poisoning time. For example, when the ambient carbon monoxide concentration is 50ppm, people may need to stay in this concentration for 8 hours before feeling headache and nausea; when the ambient carbon monoxide concentration reaches 6400ppm, people will feel extreme discomfort within 2~3 minutes, and dead within 10 minutes. Therefore, it is very necessary to detect carbon monoxide in time, it will kill you at any time.

50ppmthe maximum concentration that healthy adults can bear within 8 hours
200 ppm2 ~ 3 hours, slight headache and fatigue
400 ppmForehead pain within 1 ~ 2 hours; Life threatening after 3 hours
800ppmDizziness, nausea and spasm within 45 minutes; Loss of consciousness within 2 hours; Died within 3 hours
1600ppmHeadache, dizziness and nausea within 20 minutes; Died within 1 hour
3200ppmHeadache, dizziness and nausea within 5 ~ 10 minutes; Died within 30 minutes
6400ppmHeadache, dizziness and nausea within 1 ~ 2 minutes; Died within 10 ~ 15 minutes
12800ppmDied within 1 ~ 3 minutes
Symptoms of different concentration of carbon monoxide

For more information on symptoms of carbon monoxide poisoning click here.

2.The developmentof carbon monoxide detectors

In the 20th century, about 134 people died of carbon monoxide poisoning every year, and many people were hospitalized for accidental inhalation of carbon monoxide gas, which attracted attention, so carbon monoxide detectors were invented. This has proven to be the most effective way to effectively detect carbon monoxide and further reduce the risk of carbon monoxide poisoning. Later, with the continuous advancement of technology, carbon monoxide detectors have also been continuously upgraded(sensor change), from the earliest visual alarms to sound and light alarms, and also have many functions, such as displaying real-time CO readings, self-provided replaceable batteries, and even equips the function of detecting both carbon monoxide and fire. The invention of the carbon monoxide detector, no matter how it is improved, its ultimate goal is to immediately issue an alarm when the concentration of carbon monoxide that is threatening to the human body is detected, so that people can evacuate to the outdoors at the first time and reduce the occurrence of tragedies.

development of carbon monoxide detector-Brojensmarthome

Carbon dioxide detector

Carbon dioxide (CO2), like carbon monoxide (CO), is a colorless, odorless and imperceptible gas, but carbon dioxide has a very large impact on the environment. It is a greenhouse gas produced by people’s excessive use of energy and automobile exhaust emissions. The impact is that it causes global warming every year, melting glaciers, and rising sea levels. In addition, high concentrations of carbon dioxide can be deadly, so people have invented carbon dioxide detectors to monitor air quality and allow people to breathe cleaner air. Additionally, carbon dioxide detectors are used to monitor air quality in underground car parks and tunnels and provide valuable services in greenhouses, incubators and warehouses.

bad effect of carbon dioxide-Brojensmarthome

3.What makes carbon monoxide detector beep?

Carbon monoxide detectors have different beep modes, we need to understand the meaning of the beep modes to determine if there is a danger around or just need to replace the detector. Normally, there are three main reasons for triggering a carbon monoxide detector alarm:

Detector detects dangerous levels of carbon monoxide around

Detector low battery alarm

Detector reaches end of life

what makes co alarm go off-Brojensmarthome

In addition, there are many beeping styles of detectors with different brands, however, as long as it is a detector sold in the European market, its beep volume and method must pass EN 50291-1:2018.And the following will list them all as much as possible. This may be the most detailed collection of detector beeps in all blogs.

4.How long will a carbon monoxide detector beep?

For most of detectors, the beep duration of the carbon monoxide detector mainly depends on the beep mode. For example, a detector beeps every 30 seconds means the detector is faulty and needs to be replaced as soon as possible; 4 loud beeps indicate the presence of carbon monoxide around; a long continuous beep means the alarm has been unplugged. However, there are some other brands of detectors whose beep sounds are different from those mentioned above, because different countries and regions have different requirements for detectors, such as the UL standard in the United States and the EN standard in Europe. For example, the Fire angle brand detector, the EN standard it follows does not apply to the UL standard in the United States, so its detectors cannot be sold in the United States.

Carbon monoxide detectors sold to Europe must pass the EN 50291-1:2018 standard, which has clear requirements for beep sounds and indicator lights. For visual alarms, there must be red, yellow, and green light indicators, red for hazard alarms, yellow for fault alarms, and green for power visual indicators.

As for the beep sound, it is strictly stipulated that when the carbon monoxide concentration is higher than 50ppm, the detector must emit a beep sound. During the beep period, the mute button can be used to mute it, but within 10~15 minutes, if the concentration is still higher than 50ppm, the beep sound cannot be muted. The beep sound of all detectors sold to European brands must meet the above standards before they can enter the European market. As for 3 beeps or 4 beeps or how long when alarming, it is up to each brand to decide and print it on the manual.

requirements for mute button-Brojensmarthome
requirements for mute button

5.Problems reflected by different styles of beep

The conditions listed below are for most detectors, and there are some brands of detectors that do not match the descriptions below, such as the color of the indicator light, the number of beeps that express the problem, and so on. In these cases, please refer to the corresponding manual.


Beep once means beep once a minute,This means that the detector has low batteries and you should replace them

Beeping 2 times/beep every 30 second:

Battery needs to be replaced.
Alarm has reached end of life.
Alarm has malfunctioned

Beeping 3 times:

Three beeps, at 15-minute intervals = MALFUNCTION. The unit is malfunctioning. Contact the manufacturer or the retailer where you purchased the alarm.

Beeping 4 times:

This CO alarm pattern consists of four short beeps, followed by silence for five seconds, and then another four short beeps. Four-beep alarms are loud and continuous. It can indicate that the detector has sensed rising levels of carbon monoxide.

Beeping 4 times then stopped:

When your carbon monoxide detector chirps 4 times in a row and pauses, this means it has detected unsafe levels of carbon monoxide. This means your entire household should evacuate immediately and seek fresh air.

5 beeps:

End of life.

Beeping every 30 seconds:

Battery needs to be replaced

Alarm has reached end of life

The alarm is malfunctioning

Beeping every 15 seconds:

Low Battery.

The alarm beeps once every 15 seconds. You need to replace the batteries.

Beeping every 15 minutes:

Sometimes, smoke and CO alarms will emit a high-pitched chirp every few moments to let you know that they need your attention. Usually it’s something simple that needs to be fixed, like a low battery.

1 beep every 30 seconds:

The alarm may have a low battery when it beeps. Replace the batteries when the unit beeps every 30 seconds. Turn the unit counterclockwise to remove it and remove the old batteries. Install the new batteries into the alarm.

Beeping 3 times every 5 seconds:

Check Your CO Detector

If your detector is low on battery, you will likely hear a short chirp every minute. To warn of dangerous CO levels, most detectors will beep 4 or 5 times in a row about every 4 seconds.

Beeping once a minute:

1 Beep Every Minute: Low Battery. It is time to replace the batteries in your carbon monoxide alarm.

Beeping red:

The red light on carbon monoxide detectors depends on the brand of each detector. In general, most detectors flash a red light to indicate the presence of carbon monoxide around, but on First Alert brand carbon monoxide alarms, a flashing red light indicates that the carbon monoxide alarm is properly receiving battery power. If you don’t see the red light flashing, replace the battery in the siren immediately.

Beeping blue light:

Blue light flashes quickly when sensor detects elevated CO levels.

Beeping green light:

The flashing green light on a carbon monoxide alarm varies with each model and brand, so be sure to check with the appropriate company or user guide to verify what it means. A continuously flashing green light just means normal operation if the light is always there. This means that it is impossible to completely eliminate the alarm from the flash. Note that if the green light is accompanied by any noise, including chirps, the battery or the device itself may need to be replaced.

Beeping but light is green:

In other cases, a steady or flashing green light on a carbon monoxide detector may mean it detected low levels of carbon monoxide. If there is an increase, it will cause the alarm to go off. It could also mean it’s time to replace the battery, especially if it’s still beeping.

Beeping red and green:

This is the power light: some alarms have a red or green light that flashes every few minutes.

Beeping no light

This is largely due to the out of battery in the detector, please replace the battery in time to make the device work again.

Loud beep

A continuous set of four loud beeps—beep, beep, beep, beep—means carbon monoxide is present in your home. Go outside, call EMERGENCY service and stay out.

Long continuous beep:

An alarm malfunction – Power surges are the main culprits of malfunction, but it can also be due to other errors.

Tamper-resist warning has activated – This could be due to the device being unplugged or has become loose from its outlet.

Keeps beeping/Beeping continuously:

False positive: try restarting the device

Low battery: Most detectors support replaceable batteries

End of life: It is recommended to replace the detector with a new one as the detector will not operate even with a new battery

Beeping for no reason:

In most cases, no. There is typically a reason why the CO alarm is sounding, whether it detects carbon monoxide in the air or is low on battery.

Beeping intermittently in UK

Low Batteries – Batteries that aren’t properly installed could cause the device to sound brief and irregular chirps.

Dirty alarm sensing chambers – Dust and insects can accumulate inside the alarm sensing chambers of your device. This could cause false alarms and chirps.

Environmental factors such as: Temperature, Improper airflow, Steam, Humidity, Condensation

Power surges – Irregular chirps can sound off when the electricity comes back from a power surge. This may happen in AC-powered or hardwired carbon monoxide detectors.

Aging device – Most carbon monoxide detectors live up to 10 years. But if yours goes beyond 10 years and you’re still using it, you might begin to hear random beeps from your device.

Beeping periodically:

Most of this is programmed, like auto-restarting beeps once a day to test if the device is functioning properly.

Beeping with new batteries:

The sensors in most carbon monoxide detectors have a limited lifespan, typically 5-7 years. When this lifetime expires, the detector will begin beeping to indicate that it needs to be replaced. The detector beeps even when a new battery is replaced. If the sensor beeps before reaching the end of its life, there is a high probability that the detector is faulty and needs to be replaced with a new one.

Beeping low battery:

When the carbon monoxide detector is low on battery, it will beep to remind you to replace the battery with a new one.

Beeping during power outage

Even in a power outage, the detector’s backup battery will keep it working, and the detector will still beep if it happens to detect carbon monoxide during that time.

Beeping move to fresh air:

Newer carbon monoxide alarms have the phrase “move to fresh air” printed on the surface, reminding you to move all household members to a well-ventilated, fresh air area when the alarm goes off.

Beeping plugged into wall:

When the plug-in carbon monoxide detector is inserted into the wall and powered on, it will beep briefly to indicate that the detector is activated.

Beeping in RV:

It means that carbon monoxide is detected in the RV, you should evacuate the RV immediately and check the source of gas, generator, etc.

Beeping when power out:

When the detector has no backup battery and is powered off, the detector will beep to remind the owner that the device is powered off and needs to be powered on immediately.

Beeping without battery:

A plug-in or hard-wired carbon monoxide detector does not require a battery and can also beep when it detects carbon monoxide.

Beeping when cooking:

This means that carbon monoxide is produced during the cooking process, so you should immediately open the window for ventilation, turn off the stove, and leave the kitchen.

Beeping 888:

Whenever you press the test/reset button, the device goes through a series of numbers programmed to test the device’s internal diagnostics. This will start with a reading of 888, then display numbers usually in the 200 range, then go back to 888, then back to zero.

Beeping Lb

“Lb” is the signal for a low battery. The capital L with a lower case b on your digital display is letting you know the battery is low and needs to be replaced.

Beeping and says end

This means it has reached the end of its life and needs to be replaced. The alarm will also chirp 5 times per minute to let you know it’s time for replacement.

Beeping and reading 97

The number 97 is an indicator for “low battery”. You should try a new set of batteries, if that does not work then the alarm may be faulty.

Carbon monoxide detector goes off in middle of night

In general, carbon monoxide poisoning incidents mostly occur at night, and some people forget to turn off the gas or have poor ventilation in their homes, which leads to carbon monoxide accumulation. Therefore, when the carbon monoxide detector alarms at night, for safety consideration, regardless of whether it is a false alarm or a malfunction, you should immediately take your family members and move them to fresh air.

6.What steps should I follow when there may be carbon monoxide poisoning?

6.1. Immediately transfer people to check symptoms

When you hear an alarm from a carbon monoxide detector, immediately open the windows closest to you and check your surroundings. At the same time, immediately wake up people around you and move them to fresh air. When the family members have moved outside, you can roughly judge whether the detector has false alarms by observing the symptoms on the surface of the family members:




Chest pain


Paled face



symptoms of carbon monoxide poisoning-Brojensmarthome

These symptoms are caused by the entry of carbon monoxide into the body to displace hemoglobin in the blood to transport oxygen to various organs. In addition, if you have pets at home, you can observe whether pets have abnormal performance, because pets are affected by carbon monoxide poisoning earlier than people.

6.2. Contact emergency services

Make an emergency call outside, and do not enter the house until rescuers arrive to prevent carbon monoxide gas from remaining in the home.

call for help-Brojensmarthome

6.3. Check your carbon monoxide detector

Let an expert check your carbon monoxide detector after an emergency, which can effectively prevent the detector from falsely reporting, not reporting, and more.

6.4. Check the device when it beeps

If you’re sure that the detector is just beeping (without triggering an alarm), you can check if there is a problem with your device, here’s how:

Replace with new battery

Clean the dust on the surface of the detector

In the event of a false positive, touch the mute button to mute the device

Touch the reset button to restart the device

6.5. Check carbon monoxide detectors regularly

Carbon monoxide detectors require monthly inspections, primarily to check their physical condition, battery, and circuitry (if hardwired). Check whether the equipment is running normally by pressing the test button. If it is found that there is no alarm or the life of the detector is exhausted, you should ask a professional to repair or replace the detector with a new one.

7.How to turn off CO alarm beep

For detectors that are beeping continuously for false alarm, it can affect people’s lives if they keep beeping without turning them off. There are three main ways to close:

1. Press the Reset button to restart the detector

2. Press the mute button to mute the detector, if there is indeed carbon monoxide around and the concentration is not very high, the mute button will only mute the detector for 5~10 minutes, and then it will continue to beep

3. Replace the battery

how to turn off the beep-Brojensmarthome

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