Smoke detector chirping?

One short chirp every 30 or 60 seconds usually means the alarm's battery is low, and that goes for smoke and CO alarms alike. Chirping that keeps going after a fresh battery usually means the alarm has reached the end of its life and needs replacing.

Not sure which one it is? Snap your smoke or co detector and we’ll narrow it down.

Is it a full, loud alarm rather than a chirp?

An alarm that goes off with no fire has different causes. Smoke detector false alarm

Likely causes

  1. Low battery

    Most commonEasy DIY

    A single short chirp about every 30 or 60 seconds. It often starts at night, when the house cools and the battery's voltage dips.

  2. Alarm is at the end of its life

    Most commonEasy DIY

    It still chirps after a new battery, or the manufacture date on the back label is more than 10 years ago. Smoke alarms must be replaced after 10 years. CO end-of-life signals vary by manufacturer, so check the manual, and replace a CO alarm by the date printed on it.

  3. Battery drawer not fully closed, or pull tab still in

    CommonEasy DIY

    The chirp started right after a battery change. Check that the battery drawer or cover clicks fully shut and that any plastic pull tab on a new battery is removed.

  4. Backup battery in a hardwired alarm

    CommonEasy DIY

    The alarm is wired to the house and has a battery inside as backup. A hardwired alarm chirps when that backup battery is low, even though it has house power.

  5. Leftover error chirp after a power outage

    Less commonEasy DIY

    Chirping began after the power went out or came back on, with a good battery in. Clear it with the alarm's reset or test button as the manual describes.

  6. Dust in the sensing chamber

    Less commonEasy DIY

    The alarm is dusty or in a dusty spot and chirps or flickers for no clear reason. Vacuum around the vents with a brush attachment, or use a can of compressed air, then press the test button.

Quick checks

Never pull the battery or disable an alarm to stop a chirp. Fix or replace it the same day, because an alarm that is off can't warn you. If the alarm is sounding a full alarm rather than a chirp, treat it as real until you have checked. A CO alarm sounding means get everyone outside into fresh air and call 911 or the fire department, and never assume it is false. If the alarm is hardwired, switch off its breaker before taking it off the ceiling or wall. Test every alarm monthly.

  1. Find the alarm that is chirping: stand under each one in turn and listen for the next chirp. A chirp in a hallway can seem to come from another room.
  2. Replace the battery with a fresh one of the type printed on the alarm or in the manual, and remove any pull tab. Make sure the drawer or cover closes fully.
  3. Look at the label on the back for the manufacture date. If it is 10 years old, replace a smoke alarm. For a CO alarm, replace by the date printed on it.
  4. If it still chirps after a new battery, press the test button, then the reset button if there is one, as the manual describes, to clear a leftover error chirp.
  5. Gently vacuum or blow dust from the vents around the alarm.
  6. Write down the brand and model from the label, and photograph the front of the alarm, including any lights.
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Snap one of these:

  • the front of the alarm, including any lights
  • the label on the back with the manufacture date
  • where the alarm is mounted (near a kitchen or bathroom?)

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When to call a pro

A hardwired alarm that still chirps after a new battery and a reset, wiring that is loose or damaged, or no wiring where you need an alarm. Replacing a battery or a plug-in or battery-only alarm is a DIY job. An electrician is only needed for hardwired units or new wiring. For lifespan and upkeep, see the smoke and CO detector guide. If it is a full alarm with no fire, see smoke detector false alarm.

Typical cost: Mostly a DIY fix: a battery or a replacement alarm needs no pro. Where you do hire one, installation averages about $115 ($70–150), and an electrician charges $50–100 an hour. A hardwired alarm that needs new wiring can reach $500 or more.

Sources: HomeAdvisor: Smoke detector installation cost (updated June 19, 2026), NFPA: Learn the sounds (copy hosted by the Village of Penn Yan), US Fire Administration: Replace smoke alarms when they are 10 years old

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Related problems

  • Smoke detector false alarm?

    Smoke or CO detector

    A smoke alarm that goes off with no fire, usually cooking smoke or steam nearby, dust or insects, or an aging sensor.

  • Furnace won't heat?

    FurnaceFall

    The furnace runs but the house stays cold, which is usually a clogged filter, a thermostat setting, or an ignition fault.

  • Heat pump not heating?

    Heat pumpFall

    The heat pump runs but the house stays cold, which is usually thermostat settings, a clogged filter, or an iced-over outdoor unit.

  • Washer won't drain?

    Washer

    Water is left in the drum after the cycle, which is usually a clogged pump filter or a kinked drain hose.

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