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Carbon monoxide alarm going off or chirping? What to do

If your carbon monoxide alarm sounds, get everyone outside to fresh air and call 911. CO alarms can sound in repeating bursts with pauses. A chirp may be a maintenance warning, but don't decide from the timing alone. If you're unsure, or suspect CO even without an alarm, get outside and call for emergency help. Check your model's manual only when there is no emergency. Written for homeowners in Greenville, Spartanburg, Anderson and Pickens counties.

Published Sources listed at the end Checked against CPSC, CDC, Fire Safe South Carolina and Kidde guidance

If the alarm is sounding

  1. Get everyone outside to fresh air now, including pets if you can do it without delay. Don't try to find the source.
  2. Call 911 or your fire department from outside.
  3. Count heads to make sure everyone is out.
  4. Don't go back in until emergency responders say it's safe.

Feeling sick, even without an alarm? Carbon monoxide is colorless and odorless. Early symptoms are like the flu without a fever: headache, fatigue, shortness of breath, nausea or dizziness. CPSC advises getting outside to fresh air immediately, calling the fire department from a neighbor's home, and seeing a doctor right away; tell them you suspect carbon monoxide.

Smell gas (a rotten-egg smell)? Leave now. Don't touch switches or valves, and call 911 or your gas utility from a safe place well away from the smell.

1. Beeping or chirping: alarm or maintenance warning?

Sound patterns differ by brand and model, so check the label on the alarm or its manual when you're not in an emergency. Don't wait inside to count beeps. As one manufacturer's example, Kidde's support pages describe these patterns:

  • Carbon monoxide detected: four short beeps, five seconds of silence, then four short beeps again. Treat it as an emergency and follow the steps above.
  • A chirp once every 60 seconds: on the models Kidde describes, this may indicate a low battery. Follow your model's instructions, and don't try to open a sealed battery compartment.
  • A chirp every 30 seconds: on Kidde alarms this can mean end of life or a malfunction. Kidde says an alarm in end-of-life mode can't detect carbon monoxide.

These are examples from Kidde's support guidance, not a universal sound chart. Patterns and replacement ages vary by model, including within the same brand. Follow the label and manual for your exact alarm. Kidde also describes alarms with seven- or ten-year lifespans. An end-of-life alarm needs replacement, not just a fresh battery.

Not sure which one you're hearing? Treat it as an alarm: get outside and call 911. Don't pull the batteries to silence a sounding alarm.

2. After the alarm: what happens next

  • Stay out until responders say it's safe, even if the alarm stops.
  • Don't use a faulty appliance. If the source turns out to be a malfunctioning appliance, CPSC says not to operate it until it has been properly serviced by trained personnel.
  • Gas appliance or gas smell? Once outside, after calling for emergency help, contact your gas utility as well.
  • Heating system: CPSC recommends a professional inspection and service every year. If your heat is out while you wait, see our guide to staying warm safely.

3. Where to put carbon monoxide alarms

  • Every level and outside sleeping areas. CPSC recommends battery-operated alarms, or alarms with battery backup, on every level of the home and outside sleeping areas. CDC also advises a detector near every sleeping area.
  • Interconnected is best. CPSC notes that with interconnected alarms, when one sounds, they all sound.
  • Places to avoid. CPSC advises avoiding spots near heating vents or where furniture or curtains could cover the alarm, and doesn't recommend kitchens or spots above fuel-burning appliances.
  • Mounting height and spacing: follow the manufacturer's instructions for your model.

4. Testing and replacing alarms

  • Test at least monthly. CPSC recommends testing alarms every month; if your manual calls for more frequent tests, follow it. CPSC's fact sheet notes that the test button checks the circuitry, not the accuracy of the sensor.
  • Check replaceable batteries twice a year. CDC suggests checking them when you change the clocks in spring and fall. For sealed-battery models, follow the manual.
  • Replace the alarm on the manufacturer's schedule. CPSC says alarms have a recommended replacement age, found in the product literature or from the manufacturer, and newer alarms give an end-of-life signal. Fire Safe South Carolina, from the State Fire Marshal's office, notes that models may be rated for five, seven or ten years, and advises replacing an alarm if its date is missing or unreadable.

5. Common sources of carbon monoxide at home

CPSC lists malfunctioning fuel-burning appliances such as furnaces, ranges, water heaters and room heaters; engine-powered equipment such as portable generators; fireplaces; and charcoal burned indoors. To lower the risk:

  • Never run a car or truck in a garage attached to the house, even with the garage door open (CDC).
  • Never heat the house with a gas oven, and never use a portable gas camp stove or burn charcoal indoors (CDC).
  • Use a portable generator outdoors only, more than 20 feet from windows, doors and vents, with the exhaust pointed away from buildings (CPSC, CDC).
  • Have fuel-burning heating equipment serviced every year (CPSC, CDC).

Heat out in cold weather? Our no heat guide covers safe first checks for a furnace or heat pump.

This guide is for information only. We don't sell, install or service alarms.

Sources