Smoke and CO Detector Maintenance Checklist
Smoke and carbon monoxide detectors only work if they're maintained. Here's how often to test them, replace batteries, and swap the units entirely.
Why it matters
A smoke or carbon monoxide detector with a dead battery is worse than having none at all — it gives you false confidence. These devices are your earliest warning for two of the most serious hazards in a home, and they're only useful if they're actually working.
How often to check them
Test the alarm button monthly — that's the standard recommended by the National Fire Protection Association. Replace the batteries once a year, even if they still seem fine — most manufacturers recommend a fresh set annually regardless. Many people tie the battery swap to a clock change or another recurring date so it's easy to remember.
When to replace the whole unit
Smoke detectors have a working life of about 8–10 years, and CO detectors around 5–7 years, printed on the back of the unit. If yours is past that date, or you're not sure how old it is, replace it — sensors degrade even if the alarm still sounds when tested.
Placement matters too
Make sure you have a detector on every level of your home and outside sleeping areas. CO detectors should be near bedrooms, since carbon monoxide poisoning often happens while people are asleep.