Carbon monoxide alarm going off
A CO alarm sounding, especially with headaches or nausea.
What you're probably seeing
A CO alarm sounding, especially with headaches or nausea.
Likely causes
- A fuel-burning appliance venting poorly.
- A blocked flue or chimney.
- A cracked heat exchanger.
Safe checks you can do now
- Get everyone outside into fresh air right away.
- Call 911 or your gas utility from outside.
- Don't go back in until responders say it's safe.
When to call a pro
After responders clear the house, before using the heating again.
General information about common causes, not a diagnosis of your home.
FAQ
Quick answers
Who fixes carbon monoxide alarm going off?
A heating and cooling company. Call (844) 511-3573 to connect with an independent local heating and cooling company.
How much does it typically cost?
Furnace repair: $125–$480 (ignitor $100–$250, flame sensor $80–$250, blower motor $300–$900) (HomeGuide 2026 national ranges). Your pro sets the real number after seeing the job.
When should I call?
After responders clear the house, before using the heating again.
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