Kidde alarm signals: beeps, chirps and lights
Kidde’s US support pages describe its smoke, carbon monoxide and combination alarms as a family: most signals are a chirp at a fixed interval, and on some models the red LED flashes between chirps. The support pages cover the range rather than one model, so the owner’s manual of your model is the final word.
If it is sounding a full alarm: the maker’s emergency instruction
Smoke alarm
Kidde: never ignore the alarm. First check for fire. If there is one, wake small children and leave at once by your escape plan — do not stop to dress or collect valuables; feel a door before opening it and use another exit if it is hot; stay low in smoke; meet at your meeting place; call the fire department from a neighbour’s house; do not go back in until the fire department says it is safe.
Carbon monoxide alarm
Kidde: a sounding CO alarm means carbon monoxide, which can be fatal. Press the TEST/RESET button, call 911 or your local fire department, and move at once to fresh air — outside or by an open door or window. Account for everyone, and do not go back in until emergency services have arrived, the home has been aired out and the fire department gives the all clear.
From What Should I Do When My Carbon Monoxide Alarm Sounds?.
Every Kidde signal we could source
| What you see | What you hear | What it means |
|---|---|---|
| Red light | Full alarm, loud and continuous | Real alarm: The alarm has sensed products of combustion and is in alarm mode; the pulsing alarm carries on until the air has cleared. |
| No light named by the maker | Full alarm, four beeps then a pause, repeating | Real alarm: Kidde’s CO alarm pattern: the alarm may have sensed a dangerous level of carbon monoxide. |
| No light named by the maker | One chirp about every 30 seconds | Low battery: Low battery. |
| One red flash | One chirp, no fixed interval | Fault: Alarm malfunction. |
| No light named by the maker | One chirp about every 30 seconds | Hush or silence mode: Hush is on. |
| No light named by the maker | One chirp about every 30 seconds | End of life: End of life, on sealed-battery models only: Kidde says a chirp every 30 seconds means it is time to replace the alarm. |
| No light named by the maker | One chirp about every 30 seconds | End of life: End of life or malfunction. |
| No light named by the maker | One chirp about every 60 seconds | Low battery: Low battery on a Kidde CO alarm: one chirp every 60 seconds means the batteries need replacing. |
| No light named by the maker | Silent | Real alarm: Kidde’s rule for its digital CO alarms: any time the display shows a number, with or without an alarm, assume it is sensing carbon monoxide. |
| No light named by the maker | Silent | Low battery: A capital L with a lower-case b on the display is Kidde’s low-battery message. |
| Green light | Silent | Normal operation: Normal operation. |
| Yellow or amber light | Silent | Fault: A fault has occurred. |
Sources
Kidde’s own documents only, read on the date shown.
- Kidde: What Causes Consistent Chirping? — Kidde smoke and CO alarms, US range (support article; no single model). www.kidde.com Checked 2026-09-29.
- Kidde: What is Causing My Smoke Alarm to Sound, Beep, or Chirp? — Kidde smoke alarms, US range (support article). www.kidde.com Checked 2026-09-29.
- Kidde: What to Do When Your Smoke Alarm Sounds — Kidde smoke alarms, US range (support article). www.kidde.com Checked 2026-09-29.
- Kidde: What Should I Do When My Carbon Monoxide Alarm Sounds? — Kidde CO and combination alarms, US range (support article). www.kidde.com Checked 2026-09-29.
- Kidde: Why Is My Carbon Monoxide Alarm Beeping or Chirping? — Kidde CO alarms, US range (support article). www.kidde.com Checked 2026-09-29.
- Kidde: What do the different LED colors mean on my Smart smoke device? — Kidde smart smoke and smoke + CO alarms (support article). kidde.com Checked 2026-09-29.
- Kidde: What Causes Intermittent Beeping or Chirping? — Kidde smoke, CO and combination alarms, US range (support article). www.kidde.com Checked 2026-09-29.