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How to test smoke and carbon monoxide detectors (and how often)

By the Tagwell team · October 9, 2026

Smoke and carbon monoxide detectors fail silently. A monthly test is the only way to know they'll work when it counts. The routine takes about five minutes for a whole house.

The schedule

JobHow often
Press the test button on every detectorMonthly
Replace batteries (9V or AA models)Yearly, or when it chirps
Vacuum or blow dust out of the ventsEvery 6 months
Replace smoke detectorsEvery 10 years
Replace CO detectorsEvery 5 to 7 years (check the label)

How to test (5 minutes)

  1. Tell everyone at home you're testing so nobody panics.
  2. Press and hold the test button on each detector until it sounds. It should be loud enough to hear in every bedroom with the door closed.
  3. If detectors are interconnected, one test should set off all of them. If one stays quiet, check its connection or battery.
  4. If a detector doesn't sound, replace the battery and test again. If it still doesn't sound, replace the detector.

Check the date

Look on the back of each detector for the manufacture date. If it's more than 10 years old (or the CO detector is past its end-of-life date), replace it even if it still beeps. The sensors wear out.

Where detectors should be

  • Inside every bedroom, outside each sleeping area and on every level, including the basement.
  • CO detectors on every level and near bedrooms, especially if you have gas appliances, a fireplace or an attached garage.
  • Not right next to the kitchen or bathroom, where cooking smoke and steam cause false alarms.
Local codes vary, so check your city's rules if you're a landlord. Tagwell reminds you monthly and keeps a dated record of every test, which is handy for rentals.

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