How long does a carbon monoxide alarm last?
Typical
10 years
Range
7–10 years
CO alarms last 7–10 years depending on the sensor, and every unit has a printed expiry date — the electrochemical cell exhausts itself whether or not it ever alarms. Modern sealed-battery models are typically 10-year units.
What decides it
- The printed expiry date decides — not the battery indicator
- Placement: wrong height or a steamy bathroom shortens sensor life
- Rented homes with fixed combustion appliances: legally required in England
When to replace rather than repair
Like smoke alarms: no repair, replace at the printed date.
Typical ranges from manufacturer guidance and industry surveys — individual machines vary with use and care. General information, not advice on a specific appliance.