# Carbon monoxide detector beeping: what each beep and chirp pattern means, model by model, from the maker manuals

> Four beeps is a CO alarm on Kidde, First Alert and X-Sense units: get to fresh air and call 911. One chirp a minute is low battery; 2 to 5 a minute is end of life.

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| Source | https://ownerspec.com/air/guides/carbon-monoxide-detector-beeping-what-it-means/ |
| Publisher | OwnerSpec (https://ownerspec.com/) |
| Published | 2026-10-03 |
| Updated | 2026-10-03 |
| Facts verified | 2026-10-03 |
| Disclosure | Contains affiliate links. OwnerSpec may earn a commission at no cost to the reader. |

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## Short answer

A carbon monoxide detector sounding four beeps, a pause, then four beeps again is in CO alarm: the Kidde C3010 guide, the First Alert CO710 manual and the X-Sense XC01-M manual all print four beeps as the alarm pattern, and CPSC's instruction is to "immediately move outside to fresh air" and call emergency services, the fire department or 911. Every other pattern is the alarm reporting on itself. One chirp every 60 seconds is low battery on the Kidde C3010-D (with "Lb" on the display), the Kidde 30CUA10 combination alarm and the X-Sense XC01-M. End of life is two beeps every 30 seconds on the Kidde C3010, five chirps a minute with "End" on the First Alert CO710, and three beeps a minute on the X-Sense XC01-M. A sealed 10-year alarm at end of life does not take a battery or a reset: Kidde says the beep stops only when the alarm is out of power, so the remedy is a new alarm.

## Fact sheet

- **Answer:** Four beeps, pause, four beeps is the CO alarm pattern in the Kidde C3010, First Alert CO710 and X-Sense XC01-M manuals; CPSC says move outside to fresh air and call 911. One chirp every 60 seconds is low battery on those models. End of life is 2 beeps every 30 seconds (Kidde C3010), 5 chirps a minute (First Alert CO710) or 3 a minute (X-Sense XC01-M): a sealed 10-year unit is replaced, not reset.
- **Basis:** The beep, chirp, display and LED patterns printed in the Kidde C3010/C3010-D and 30CUA10 user guides, the First Alert CO710 user's manual, the X-Sense XC01-M user manual and Google's Nest Protect help page, plus the alarm-response steps printed by CPSC and Kidde.
- **Assumptions:** Each pattern is attributed to the model whose manual prints it; the same chirp count means a different thing on a different model, so no pattern is stated as a brand-wide rule; The Kidde COB10 manual was not opened, so no beep pattern is attributed to it; only Kidde's 10-year life statement applies; No Nest Protect page read states its low-battery or end-of-life message for the CO sensor, so the Nest row covers only the Heads-Up and Emergency alerts
- **Method:** Spec comparison of maker-published alarm patterns and the alarm-response steps printed by CPSC and Kidde, read on 2026-10-03. No alarm was tested or triggered. Prices on the product cards are Amazon's live figures and are never written into this page.
- **Primary source:** [Kidde C3010 / C3010-D user guide](https://www.shareddocs.com/hvac/docs/2001/Public/0C/User-Guide-C3010-C3010-D-Eng.pdf) (manufacturer or vendor document)
- **Facts verified:** 2026-10-03
- **Last updated:** 2026-10-03
- **Canonical URL (cite this):** https://ownerspec.com/air/guides/carbon-monoxide-detector-beeping-what-it-means/

If the alarm is doing four beeps right now, close this page and get outside: everything below is for reading after the fire department has cleared the house.

## Which beep pattern is it?

Count the beeps, note the gap between groups, and look at the LED or display. The same count means different things on different models, so match the row to the model number on the back.

The alarm patterns, which call for action, as each maker prints them:

| Pattern | Model | Meaning | Where it is printed |
| --- | --- | --- | --- |
| 4 quick beeps, 5 seconds of silence, repeating; red LED flashes with the beeps | Kidde C3010 / C3010-D | CO alarm. Repeats for the first 4 minutes, then two 4-beep groups once a minute while the condition lasts | Kidde C3010 user guide |
| 4 quick beeps repeating every 5 seconds | Kidde 30CUA10 (smoke + CO) | CO alarm. Smoke is a different sound: three long beeps, a 1.5 second pause, three long beeps | Kidde 30CUA10 user guide |
| 4 beeps, pause, 4 beeps; blue backlight glows | First Alert CO710 | CO alarm, 85 dB | First Alert CO710 manual |
| 4 beeps every 5.8 seconds; LED flashes red | X-Sense XC01-M | CO alarm; interconnected units repeat the same 4 beeps | X-Sense XC01-M manual |
| Red pulsing light, loud sound, spoken message ("Emergency: there's carbon monoxide in the basement. Move to fresh air.") | Nest Protect | Emergency alarm; cannot be disabled | Google Nest Help |
| Yellow pulsing light, gentle spoken message | Nest Protect | Heads-Up for a low level of CO or smoke; silenced by pressing the Nest button | Google Nest Help |

The self-report patterns, which call for a battery, a reset or a new alarm:

| Pattern | Model | Meaning | Where it is printed |
| --- | --- | --- | --- |
| 1 quick beep every 60 seconds, "Lb" on the display, amber LED every second | Kidde C3010-D | Low battery. Warm a cold unit above 68 F; if it still beeps at room temperature, replace the unit | Kidde C3010 user guide; Kidde CO support page |
| 1 chirp every 60 seconds, amber LED every 60 seconds | Kidde 30CUA10 | Low battery | Kidde 30CUA10 user guide |
| 1 chirp and yellow LED every 60 seconds | X-Sense XC01-M | Low battery | X-Sense XC01-M manual |
| 2 beeps every 30 seconds, after 10 years from power-up | Kidde C3010 / C3010-D | End of life. "It will not detect CO in this condition." Replace immediately | Kidde C3010 user guide |
| 1 quick beep every 30 seconds, red LED flashes | Kidde non-digital CO alarms | End of the 7- or 10-year life | Kidde replacement FAQs |
| 2 chirps every 60 seconds, amber LED blinks twice | Kidde 30CUA10 | End of unit life | Kidde 30CUA10 user guide |
| 5 chirps every minute, "End" on the display | First Alert CO710 | End of life | First Alert CO710 manual |
| 3 beeps and yellow LED 3 times every 60 seconds | X-Sense XC01-M | End of life, after the 10-year maximum lifetime | X-Sense XC01-M manual |
| 1 quick beep every 30 seconds, amber LED every second, green LED blinking a code | Kidde C3010 / C3010-D | Error. Hold Test/Reset 5 seconds; if it keeps beeping, slide the shutdown switch on the back | Kidde C3010 user guide |
| 3 chirps every 60 seconds | Kidde 30CUA10 | CO sensor fault | Kidde 30CUA10 user guide |
| 3 chirps every minute, "Err" on the display | First Alert CO710 | Malfunction; replace the unit | First Alert CO710 manual |
| Constant tone | Kidde C3010 / C3010-D; Kidde 30CUA10 | Very low battery or unit malfunction (C3010); MCU failure (30CUA10) | Both Kidde guides |

Three chirps a minute is a sensor fault on a Kidde 30CUA10 and a malfunction on a First Alert CO710, but end of life on an X-Sense XC01-M. A generic "chirps per minute" rule gets at least one model wrong.

No pattern is listed for the Kidde COB10 or any Nest Protect battery message, because no manual stating them was opened for this page. A digital display that says "Lb", "End" or "Err" settles the question without counting; the [best carbon monoxide detector](/air/reviews/best-carbon-monoxide-detector/) comparison notes which current units have one.

## What do you do when it is four beeps?

The response is the makers' and CPSC's words, not this site's. CPSC: "Immediately move outside to fresh air. Call your emergency services, fire department, or 911." Then "do a head count to check that all persons are accounted for. DO NOT reenter the premises until the emergency services responders have given you permission." CPSC adds: "Never ignore an alarming CO alarm!" and says not to try to find the source yourself.

Kidde's C3010 guide puts a button press first: "Operate the Test/Reset button; Call your emergency services (Fire Department or 911); Immediately move to fresh air - outdoors or by an open door/window." It continues with a head count and "Do not reenter the premises" until responders have arrived, the premises have been aired out and the alarm is back in its normal condition. If the alarm reactivates within 24 hours, Kidde says to repeat the steps and call a qualified appliance technician.

The two orders differ by one step: CPSC leads with fresh air, Kidde with the Test/Reset button. Kidde's alarm-action page also says to check for a running engine in an attached garage. Neither source says to open windows and wait it out.

Silencing an alarm does not end it. The First Alert CO710 manual's silence lasts about 4 minutes, after which the horn returns to 4 beeps, pause, 4 beeps if CO remains, and the manual says the feature "is for your convenience only and will not correct a CO problem." The X-Sense XC01-M manual's silence mode runs 9 minutes, and the alarm triggers again if CO is still above 50 ppm after 6 minutes.

## Why does a sealed alarm keep chirping after a new battery?

Because the chirp is not about the battery. Kidde's replacement page states: "An end-of-life or sensor error will not respond to a battery change" and "The beep will only stop when the alarm is out of power." Kidde's replacement FAQs repeat it for the non-digital models.

End of life is the date, set by the maker, after which the sensor is no longer trusted. Kidde's replacement page says all Kidde CO alarms have a 10-year life as of 2013, with older units at 7 years. The First Alert CO710 manual says to install a new alarm at the end of its service life or after 10 years, whichever comes first. The X-Sense XC01-M manual gives a 10-year maximum and tells the owner to write the first-operation date on the side label. CPSC says the replacement age is in the product literature or available from the manufacturer.

A hush is a timed silence of a self-report chirp, and it is the only thing a sealed unit offers at end of life:

| Model | Signal hushed | Hush window, as printed |
| --- | --- | --- |
| First Alert CO710 | End-of-life chirp | 8 hours per press, up to 7 days |
| Kidde 30CUA10 | Low-battery and end-of-life chirps | 24 hours per push; cannot be silenced 7 days after the chirps begin |
| X-Sense XC01-M | Low-battery chirp | 10 hours per press of the test button |
| X-Sense XC01-M | End-of-life signal | 22 hours per press, 30 days in total, then it cannot be silenced; CO monitoring continues during that time |
| Kidde C3010 / C3010-D | End-of-life beeps | No hush listed; the guide says "Replace unit immediately" |

A sealed unit has no battery door, so the C3010-D low-battery row and every end-of-life row end the same way: a new alarm. The X-Sense XC01-M manual lists a replaceable battery; the hardwired Kidde 30CUA10 has a sealed backup, and its guide says to replace the unit within 7 days of low battery.

**Before you buy a replacement**

Match the model number to the table first. An X-Sense XC01-M chirping once a minute wants a battery; a Kidde 30CUA10 wants replacing within 7 days. Any end-of-life row wants a new alarm. If the back says 2015 or earlier, Kidde's 7- to 10-year window has run out whatever it is doing. Two sealed 10-year units, in stock today: the First Alert 10-year digital CO alarm and the Kidde COB10. The [best carbon monoxide detector](/air/reviews/best-carbon-monoxide-detector/) page compares them on published specs.

## What should you do first?

1. Four beeps or a red pulsing Nest: get everyone to fresh air and call 911 or the fire department, as CPSC prints it. Read nothing else until responders clear the house.
2. Any other pattern: read the model number off the back and find its row in the self-report table; a digital display showing "Lb", "End" or "Err" settles it.
3. One chirp a minute on an X-Sense XC01-M: change the battery. On a sealed Kidde C3010-D, warm it above 68 F; if it still chirps, it is a replacement. On a Kidde 30CUA10, replace the unit within 7 days.
4. Any end-of-life row: hush it for the window the manual allows and install a new alarm; the hush buys hours, not years.
5. A combination unit making three long beeps instead of four short ones is the smoke side, which the [smoke detector chirping](/air/guides/smoke-detector-chirping-low-battery-end-of-life/) guide covers.

## Frequently asked questions

### Why is my carbon monoxide detector beeping 4 times?

Four beeps is the carbon monoxide alarm pattern. The Kidde C3010 guide prints 4 quick beeps followed by 5 seconds of silence, the First Alert CO710 manual prints 4 beeps, pause, 4 beeps, and the X-Sense XC01-M manual prints 4 beeps every 5.8 seconds. CPSC's instruction is to immediately move outside to fresh air and call emergency services, the fire department or 911.

### Why does my carbon monoxide detector chirp once every minute?

On the Kidde C3010-D, the Kidde 30CUA10 combination alarm and the X-Sense XC01-M, one chirp every 60 seconds is the low-battery signal. The Kidde C3010-D shows 'Lb' on its display and flashes the amber LED every second; its guide says to let a cold unit warm above 68 F, and to replace the unit if it still beeps at room temperature, because its battery is sealed.

### Why is my carbon monoxide detector still chirping after I changed the battery?

Kidde's replacement page says an end-of-life or sensor error will not respond to a battery change, and that the beep only stops when the alarm is out of power. End of life is 2 beeps every 30 seconds on the Kidde C3010, 5 chirps a minute on the First Alert CO710 and 3 beeps a minute on the X-Sense XC01-M. Each manual's remedy is a new alarm.

### Can you silence the end-of-life chirp on a carbon monoxide alarm?

Only for a limited window, and only on models that print one. The First Alert CO710 manual silences its end-of-life chirp for 8 hours per press, up to 7 days. The Kidde 30CUA10 guide allows 24 hours per push and no silencing 7 days after the chirps begin. The X-Sense XC01-M manual allows 22 hours per press, 30 days in total. The Kidde C3010 guide lists no hush.

### How long does a carbon monoxide detector last?

Kidde's replacement page says all Kidde carbon monoxide alarms made since 2013 have a 10-year life, with older models at 7 years. The First Alert CO710 manual says to install a new alarm when it reaches the end of its service life or after 10 years, whichever comes first. The X-Sense XC01-M manual gives a 10-year maximum lifetime and says to write the first-operation date on the side label.


## Sources

- [Kidde C3010 / C3010-D user guide](https://www.shareddocs.com/hvac/docs/2001/Public/0C/User-Guide-C3010-C3010-D-Eng.pdf) (manufacturer or vendor document)
- [Kidde 30CUA10 combination smoke and CO alarm user guide](https://www.shareddocs.com/hvac/docs/2001/Public/03/Product_UG_30CUA10_0124.pdf) (manufacturer or vendor document)
- [Kidde, Carbon monoxide alarm replacement](https://www.kidde.com/support/carbon-monoxide-alarms/replacement) (manufacturer or vendor document)
- [Kidde, CO alarm replacement FAQs (end of life signal)](https://www.kidde.com/support/carbon-monoxide-alarms/replacement-faqs) (manufacturer or vendor document)
- [Kidde, Carbon monoxide alarm support (Lb display)](https://www.kidde.com/support/carbon-monoxide-alarms) (manufacturer or vendor document)
- [Kidde, What to do when your CO alarm sounds](https://www.kidde.com/support/carbon-monoxide-alarms/co-alarm-action) (manufacturer or vendor document)
- [First Alert CO710 user's manual (10-year sealed battery, digital display)](https://support.firstalert.com/sfc/servlet.shepherd/document/download/0694x00000PjfbKAAR) (manufacturer or vendor document)
- [X-Sense XC01-M user manual](https://cdn.shopify.com/s/files/1/0115/9223/7122/files/Manual_XC01-M_20240506.pdf?v=1714982614) (manufacturer or vendor document)
- [X-Sense, User manuals index](https://www.x-sense.com/pages/user-manuals) (manufacturer or vendor document)
- [Google Nest Help, Nest Protect Heads-Up and Emergency alarms](https://support.google.com/googlenest/answer/9249081?hl=en) (manufacturer or vendor document)
- [CPSC, Carbon Monoxide Questions and Answers](https://www.cpsc.gov/Safety-Education/Safety-Education-Centers/Carbon-Monoxide-Information-Center/Carbon-Monoxide-Questions-and-Answers) (government or regulatory source)

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