How to test smoke and carbon monoxide alarms
Updated . By the OakTend team.
Press the test button on every smoke alarm and carbon monoxide (CO) alarm in the house, keep the batteries fresh, and swap out any alarm that has reached its age limit.
Why it matters
An alarm only protects you if it still works, and nothing tells you it has quietly failed except a test. California also changed the rules for new alarms: a battery-only smoke alarm sold here must have a sealed battery rated for at least 10 years and show its manufacture date on the device.
Steps
- Tell everyone at home that you are testing, so nobody panics.
- Press and hold the test button until the alarm sounds. If your alarms are interconnected, check that the others sound too.
- Repeat on every smoke alarm and every CO alarm, on every floor.
- Lightly vacuum the vents on each alarm to clear dust.
- If an alarm uses a replaceable battery, change it at least once a year, and right away if it chirps. A sealed 10-year alarm has no battery to change; replace the whole alarm when it reaches its end of life.
- Find the manufacture date printed on each alarm. Replace any smoke alarm 10 years past that date, and any CO alarm at the age its maker gives.
- Check coverage: smoke alarms inside each bedroom, outside each sleeping area and on every level; CO alarms on every level and outside sleeping areas.
When to call a pro
Call a licensed electrician if a hardwired alarm keeps chirping or fails after you replace it, since the wiring or the interconnect may be the problem.
Safety
The CPSC notes that pressing the test button checks the alarm's circuits, not the accuracy of its CO sensor, which is why age matters. If a CO alarm goes off for real, get everyone outside before you do anything else.
Go deeper
General information, not professional advice. Your equipment's manual comes first when it says something different.
Sources
- U.S. Fire Administration: smoke alarms
Test smoke alarms monthly, replace them 10 years from the manufacture date, change 9-volt batteries at least once a year, and where to place them. - California Health and Safety Code section 13114
Battery-only smoke alarms sold in California need a nonreplaceable battery that lasts at least 10 years, and must display the date of manufacture. - U.S. Consumer Product Safety Commission: carbon monoxide questions and answers
Put CO alarms on every level and outside sleeping areas; the test button checks the circuitry, not the sensor's accuracy. - Orange County Fire Authority: smoke alarms and home escape plan
Test smoke alarms once a month and replace the alarm every 10 years. Checked 2026-09-21.