Why is my carbon monoxide detector going off with nothing running?

Author: Dr. Jaiden Rutherford  |  Last update: Friday, November 21, 2025

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.

What can falsely set off a carbon monoxide detector?

Common causes of false alarms of carbon monoxide:
  • Close to cooking sources (10 feet minimum)
  • Close to sources of humidity (10-20 feet)
  • Near fireplaces.
  • Near water heaters.
  • Near furnaces.
  • Located in a poorly ventilated location like a garage, kitchen, or closet.

Can a carbon monoxide detector go off for no reason?

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.

Why would the carbon monoxide alarm go off randomly?

CO alarms become erratic once expired. This is the most common reason for false alarms. Excessive moisture from a bathroom may set off your CO alarm. CO alarms should not be installed in areas with excessive steam. Lead acid battery chargers produce hydrogen gas which sets off CO detectors.

What else can trigger a carbon monoxide alarm?

Operating gas-powered vehicles or yard equipment in the garage-Attached garages pose the greatest risk of CO exposure. Still, free-standing garages can also be dangerous if you run the equipment too long. Even with the doors and windows open, any of these activities can trigger carbon monoxide detectors.

What Do I Do if My Carbon Monoxide Alarm Goes Off?

What if the carbon monoxide detector goes off 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. Contact 911 or your local fire department to report the incident.

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.

Should I call 911 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.

Can cold cause carbon monoxide detector to go off?

Do Hot or Cold Temperatures Affect My Alarm? Our smoke, carbon monoxide, and combination alarms will perform between 40 and 100 degrees Fahrenheit. If the temperature drops, the battery may be impacted by the cooler temperature and chirp as it will read as, "Low."

How to tell if carbon monoxide is in the air?

The best way to alert you and your family to unsafe levels of CO is to install a carbon monoxide detector. It works like a smoke alarm, sampling the air in your home and creating a loud alarm when levels of the gas are detected. It's important to evacuate your home immediately when your CO alarm sounds.

Can other things set off a carbon monoxide detector?

In domestic properties, your CO alarm can be triggered by any fuel burning appliance such as gas cookers, boilers and ovens. All of these appliances give off small traces of CO, but the levels can rise slightly when adequate ventilation isn't provided, or the venting is blocked or clogged by dust.

Can a carbon monoxide detector go off without power?

If you've recently experienced a power outage, you may have heard your hardwired alarms sound. If your carbon monoxide detector is beeping after a power outage, it could be because a false alarm has been triggered, or it could be a signal of CO detection.

What could cause carbon monoxide in a bedroom?

The most common causes of carbon monoxide building up are incorrectly installed or poorly maintained or ventilated appliances – like stoves and hot water heaters. Poorly ventilated fireplaces and other gas- or wood-burning appliances can also pose danger.

What other gases can set off a carbon monoxide detector after?

Carbon monoxide alarms are vital pieces of safety equipment used to protect workers and residents from poisonous carbon monoxide gas. But, did you know that hydrogen gas from charging batteries can set off the alarms as well.

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 to silence first alert carbon monoxide alarm?

Push and hold the silence button for 5 seconds to silence the alarm while contamination is being burned off the sensor. You may need to do this a number of times to give the carbon monoxide alarm enough time to reset.

Why is my carbon monoxide alarm going off randomly?

The carbon monoxide alarm going off could mean the gas is present in your home or office, or simply indicating the battery or alarm needs replacing.

How to tell if a carbon monoxide alarm is false?

4 beeps and a pause: This means that there is carbon monoxide in the air and you should seek fresh air immediately and call 911. 1 beep every minute: This means that the alarm has low batteries and you should replace them. 3 beeps every minute: This means the alarm has encountered a malfunction and needs replacement.

What if the carbon monoxide alarm goes off then stops?

If you hear 4 beeps and then a pause, this is an EMERGENCY.

It indicates carbon monoxide has been detected and you should immediately evacuate your home or building and call 9-1-1.

Will opening a window help with carbon monoxide?

If you experience symptoms that you think could be from CO poisoning: DO GET FRESH AIR IMMEDIATELY. Open doors and windows, turn off combustion appliances and leave the house.

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.

How to test a carbon monoxide alarm?

How to test your carbon monoxide detectors to ensure they are working properly? To test your carbon monoxide detectors, press and hold the test button on the alarm. The detector will sound 4 beeps, a pause, then 4 beeps for 5-6 seconds. Refer to the user manual for your specific model.

How to clear carbon monoxide from a house?

If no one is feeling symptoms, ventilate the home with fresh air and turn off all potential sources of CO. That includes your oil or gas furnace, gas water heater, gas range and oven, gas dryer, gas or kerosene space heater, and any vehicle or small engine.

What are the symptoms of gas leak exposure?

Symptoms from a natural gas leak may include:
  • headaches, sometimes severe.
  • dizziness.
  • fatigue.
  • nausea.
  • irregular breathing.
  • chest pains.
  • memory problems.
  • blurred vision.

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