Furnace runs but carbon monoxide detector in the home alarms during operation.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Emergency safety: If a CO detector alarms, turn off the furnace, ventilate the home, and evacuate if levels are high. Contact emergency services or your gas utility.
- Do not operate furnace: Leave the furnace off until it has been inspected.
- Visual vent check: From a safe position, verify that vent pipes are connected and not obviously blocked.
Only a licensed HVAC technician with combustion analysis equipment should return the furnace to service after a CO event.
Repair Difficulty
Required Part
We may earn a commission from links on this page.