How do I know if my alarm is going off for carbon monoxide?

Author: Mr. Lorenza Stoltenberg  |  Last update: Tuesday, August 19, 2025

The types of sounds and beeps the detector makes are important. Alarms that are continuously going off with a high-pitched sound mean there is a carbon monoxide leak.

How do I know if my carbon monoxide alarm went off?

4 beeps and a pause: This means that there is carbon monoxide in the air and you should seek fresh air immediately and call 9-1-1. 1 beep every minute: This means that the detector has low batteries and you should replace them.

What will my alarm do if it detects carbon monoxide?

When the carbon monoxide alarm senses a dangerous level of CO gas, the unit will emit a loud alarm pattern. The alarm pattern is four short beeps – followed by five seconds of silence – followed by four short beeps.

How do I know if there is carbon monoxide in my house?

Signs of a carbon monoxide leak in your house or home

Stale, stuffy, or smelly air, like the smell of something burning or overheating. Soot, smoke, fumes, or back-draft in the house from a chimney, fireplace, or other fuel burning equipment. The lack of an upward draft in chimney flue. Fallen soot in fireplaces.

Will opening windows get rid of carbon monoxide?

Opening windows helps the carbon monoxide quickly leave your home (as does opening doors). However, don't leave your exit path when getting out during this emergency to open as many windows as you can. Only open those that are along the way as you leave your home safely.

What to Do if Carbon Monoxide Alarm is Going Off

How can you tell a carbon monoxide alarm?

In our latest video, we asked the National Fire Protection Association what the noises mean and how to stay safe from fires and carbon monoxide. Here's a simple guide: Smoke alarms alert you with three beeps in a row. Carbon monoxide alarms alert you with four beeps.

Should I call 9-1-1 if my carbon monoxide alarm goes off?

My carbon monoxide alarm is sounding. What should I do? Call 911 and report what is happening. Immediately leave your residence and wait for the fire department to arrive.

What if carbon monoxide alarm goes off but no fire?

Your carbon monoxide alarm is going off for one of the following reasons: It is doing its job properly and detects CO pollution in the air. It is a false alarm caused by other household items. The detector is malfunctioning or the batteries need changing.

How can I be sure my carbon monoxide detector is working?

If you're wondering how you can check that your carbon monoxide detector works, the answer is simple: testing. You should test your CO detector monthly to ensure your family's safety. The test button is the best way to test it because it will tell if the alarm is still sounding.

Does a carbon monoxide alarm sound continuously?

A CO alarm that beeps continuously without stopping could indicate that carbon monoxide is present. If you your CO alarm is sounding continuously and you have signs of CO poisoning such as dizziness, headache, vomiting or flu like symptoms, find fresh air and call 9-1-1 immediately.

What to do if a carbon monoxide alarm goes off and then stops?

If you have a carbon monoxide detector chirping and then it stops, it's important to take the situation seriously, even if the alarm is no longer sounding. Even if the alarm has stopped, get everyone out of the home to a place with fresh air.

How much carbon monoxide before alarm goes off?

"According to UL Standard 2034, home carbon monoxide detectors must sound a warning before carbon monoxide levels reach 100 parts per million over 90 minutes, 200 parts per million over 35 minutes or 400 parts per million over 15 minutes.

Does the fire department charge to check for carbon monoxide?

In most areas, the fire department does not charge to respond to carbon monoxide alarms or to check for the presence of CO in a residence. However, policies can vary depending on the jurisdiction or specific fire department. It's always a good idea to contact your local fire department for specifics on their policies.

Do carbon monoxide detectors give false alarms?

While CO detectors are designed to be reliable, various factors can cause them to beep erroneously. False alarms can be caused by incorrect installation, placement near a source of fumes or steam, or even a buildup of dust and dirt on the sensor.

What are two warning signs of carbon monoxide poisoning?

The most common symptoms of CO poisoning are headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion. CO symptoms are often described as “flu-like.” If you breathe in a lot of CO, it can make you pass out or kill you.

How to tell if a carbon monoxide detector is going off?

To warn of dangerous CO levels, most detectors will beep 4 or 5 times in a row about every 4 seconds. Do not mistake dangerous levels of poisonous gas for a detector with low battery!

Should you open windows if the carbon monoxide alarm goes off?

If your CO detector goes off and you feel ill, leave the house and call 911 or the local fire department. If you do not feel ill, push your detector's reset button. If the alarm goes off again after a few minutes, open the windows, leave the house and call 911 or the local fire department.

How to tell if carbon monoxide is in your house?

It is also a good idea to know the signs of a potential CO problem:
  1. Streaks of soot around fuel-burning appliances, or fallen soot in a fireplace.
  2. Absence of an upward draft in your chimney.
  3. Excess moisture and condensation on windows, walls and cold surfaces.
  4. Rusting on flue pipes or appliance jacks.

Why do carbon monoxide alarms go off at night?

It is possible to have a carbon monoxide detector going off without any danger present. If you suspect that this is the case, it's important not to ignore it. This could be due to a faulty device, old batteries, or just dust buildup in the unit itself.

How long does it take for carbon monoxide to kick in?

How long does it take to get carbon monoxide poisoning? In high concentrations of carbon monoxide, it can take fewer than five minutes to get carbon monoxide poisoning. Under lower concentrations, it can take an hour to two hours to cause poisoning.

How do you check for carbon monoxide without a monitor?

What Are Signs of Carbon Monoxide in Your Home?
  1. Yellow or orange flames coming out of your gas appliances instead of the usual blue flame.
  2. Dark and sooty staining on or around gas appliances.
  3. Pilot lights that frequently blow out.
  4. Increased condensation on windows.
  5. Solid fuel fires burn much slower than usual.

How long does it take for an alarm to detect carbon monoxide?

If detected over the course of a few hours, carbon monoxide at 70 ppm will trigger an alarm. At the other end of the spectrum, dangerous concentrations above 400 ppm will do the same after just a few minutes.

Should I call 911 if my carbon monoxide alarm goes off?

CO detectors are very sensitive and designed to alert occupants before CO reaches dangerous levels. If your detectors go off, call 911 and evacuate the home. Be sure to notify them if anyone in the house is experiencing flu-like symptoms.

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