What to Do If Your CO Detector Goes Off

Immediate Steps

Get everyone out of the house immediately, including pets. Do not stop to investigate the source. Call 911 or your local fire department from outside. Do not re-enter until emergency responders have cleared the home. Open windows and doors if you can do so quickly and safely on your way out, but do not delay evacuation to do so.

Common Causes

Malfunctioning gas furnace or cracked heat exchanger. Blocked flue or chimney preventing exhaust from venting outdoors. Gas water heater backdrafting. Running a car or gas-powered equipment in an attached garage. Gas stove or oven malfunction. A running generator too close to the house.

After the Emergency

Once the source has been identified and resolved by emergency responders or an HVAC technician, consider having your home's combustion appliances professionally inspected. If the alarm was triggered by a malfunctioning appliance, the conditions that led to the malfunction may apply to other appliances in the home. An air quality assessment can evaluate overall combustion exposure risk across all gas appliances in the home.