Will my smoke detector go off for carbon monoxide?

Author: Margarette McGlynn  |  Last update: Monday, August 18, 2025

Fires can produce carbon monoxide, so a smoke alarm won't always detect this gas. On the other hand, carbon monoxide can be present without any visible smoke or flames, making a smoke alarm insufficient for protection.

How do I know if my smoke detector detects carbon monoxide?

How do I know if my smoke detector is also a carbon monoxide detector? Check the device for labeling or markings that indicate it is a combination unit. The manufacturer's manual or product specifications will also confirm if the detector can sense both smoke and carbon monoxide.

Will carbon monoxide set off the smoke alarm?

Most of the time, when one of these detectors sounds an alarm, the other one won't go off as well. That's because you'll often have smoke present with no carbon monoxide present, or vice versa. However, the alarms in both types of detector could sound at the same time for some fires.

Why did my fire alarm randomly go off then stop?

All your fire alarms might be going off because of low batteries, dust or insects inside the alarms, steam or humidity, or a malfunction. Try resetting them, replacing the batteries, and cleaning the alarms. If they keep going off, you might need to replace old alarms or check for wiring issues.

How to tell if carbon monoxide is leaking?

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.

What Most Homeowners Don’t Know About Carbon Monoxide Detectors

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.

Why did my smoke alarm go off in the middle of the night for no reason?

Accumulation of Debris

A smoke alarm is a sensitive device that helps to detect smoke particles from different sources of fire. Debris such as dust or soot often produced by burning matter can accumulate on the gadget thereby triggering the alarm even when there is no actual fire.

What if the carbon monoxide alarm goes off but no fire?

False or nuisance alarms are when your smoke detector or CO alarm goes off, but there is no presence of smoke or carbon monoxide in your home. However, if your smoke or carbon monoxide detector sounds indicating an emergency and you are not certain it is a nuisance alarm, evacuate the home and call 9-1-1.

Do first alert smoke detectors detect carbon monoxide?

First Alert's Precision Detection Advanced Sensing Technology. Voice & Location Alerts for Danger and Helps Escape Safely. Provides Reliable 2-in-1 Protection Against Both Smoke and Carbon Monoxide.

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.

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.

What if smoke and carbon monoxide detector went off then stopped?

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.

Do smoke alarms go off for carbon monoxide?

Fires can produce carbon monoxide, so a smoke alarm won't always detect this gas. On the other hand, carbon monoxide can be present without any visible smoke or flames, making a smoke alarm insufficient for protection.

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.

What is the easiest way to detect carbon monoxide?

A portable CO detector can be useful for detecting carbon monoxide levels near all gas-powered appliances. It's a handy way to check every room of the house. These units can be hardwired with battery backup, or you can choose a battery powered model.

How to tell if your smoke detector is also a carbon monoxide detector?

CO alarms and combination CO alarms are always clearly labeled even though many smoke detectors are not. Another way to verify whether your devices can detect both CO gas and smoke is by pressing their test buttons. Modern, hard-wired units will issue verbal alerts such as “Warning!

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.

Why did my smoke alarm go off and then stop?

The most likely reason that cause fire alarm randomly going off is that people forget to change the batteries in fire alarm devices regularly. The second most common reason is food preparation. Also, sensors set close to the fireplaces can be sensitive to smoke.

Why would a smoke alarm go off if there was no smoke?

Water vapours can develop inside the smoke sensor causing smoke alarms to react the same way as it does smoke. Once humidity reaches 85%, false alarms could frequently occur. Insects and dust are a common cause of false alarms. Steam from bathrooms and laundry can cause a smoke alarm to activate.

Why is the red light blinking on my smoke alarm?

The batteries are low: A blinking red light, usually accompanied by a loud beep, could mean the batteries in the unit are low. Consider adding fresh batteries and testing to ensure they're working. You need to replace it: Smoke detectors don't last forever.

What does a carbon monoxide alarm sound like?

Here's a simple guide: Smoke alarms alert you with three beeps in a row. Carbon monoxide alarms alert you with four beeps. A single chirp means the battery is low or the detector should be replaced.

What to do if fire alarm goes off and says carbon monoxide?

Immediately evacuate the building to fresh air and safety. Call 9-1-1 once safely outside to report the incident and if there is anyone experiencing carbon monoxide poisoning symptoms like headaches, dizziness and vomiting. Do not return into the building until it has been cleared by first responders.

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 do you tell if you have carbon monoxide in your house?

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

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