My CO alarm went off near my furnace. What do I do?
Get everyone outside immediately, leave the furnace off, and call 801-407-9320. Don't ignore a CO alarm — even brief exposure above 70 ppm can cause headaches and nausea, and sustained exposure is lethal.
Get everyone outside immediately, leave the furnace off, and call 801-407-9320. Don't ignore a CO alarm — even brief exposure above 70 ppm can cause headaches and nausea, and sustained exposure is lethal.
A carbon monoxide alarm near your furnace should never be ignored, even if symptoms seem mild. Get everyone (and pets) out of the house into fresh air first. Then, if you can do it without re-entering, turn off the furnace at the emergency switch or the gas shutoff. Call 801-407-9320 from outside.
If anyone is experiencing symptoms (headache, dizziness, nausea, confusion), call 911 first — CO poisoning is an oxygen-deprivation event and can progress fast.
The most common causes are a cracked heat exchanger (furnace usually needs replacement), a blocked flue (bird nest, ice, debris), or a malfunctioning vent damper. Do not run the furnace again until a licensed technician has tested combustion and confirmed it's safe.
Need help with this at your home?
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Last reviewed April 1, 2026.