Read the device label
NFPA guidance says to replace CO alarms within the manufacturer’s stated service life, commonly five to ten years. Look for a manufacture date, install-by date or replace-by date on the unit and its instructions.
Know the end-of-life signal
Many CO alarms use a specific chirp or display message when the sensor has aged out. That signal is not fixed by installing a fresh battery; the alarm itself is due for replacement.
Do not troubleshoot an active CO alarm
If the alarm indicates carbon monoxide, move everyone to fresh air and call 911. Replacement-age research can wait until emergency responders say it is safe to return.
Check the entire household set
Homes often contain alarms installed in different years. When one expires, inventory the others so the next end-of-life warning is not a surprise.
Safety references
Primary sources used for this page:
Manufacturer instructions and current local requirements control. For an emergency, call 911.