First Alert alarm signals: beeps, chirps and lights
The First Alert SM210L is a smoke-only alarm with a 10-year sealed battery and an escape light. It speaks in green flashes plus a count of chirps each minute: three chirps, five chirps with one green flash, and five chirps with five green flashes are three different messages. Other First Alert models use other patterns, so these pages hold for the SM210L and name it every time.
If it is sounding a full alarm: the maker’s emergency instruction
Smoke alarm
First Alert (SM210L manual): if the alarm sounds, get everyone out of the house immediately — do not stop to dress or collect anything. Feel doors with the back of your hand and do not open a hot one; cover your nose and mouth with a damp cloth; meet at your planned place outside and count heads; call the fire department from outside, giving your address and then your name; never go back inside a burning building.
From User’s Manual — Smoke Alarm, 10-Year Sealed Battery with Escape Light.
The First Alert alarm on these pages senses smoke only. For a carbon monoxide alarm, follow its own maker’s instruction.
Every First Alert signal we could source
| What you see | What you hear | What it means |
|---|---|---|
| One green flash about every 60 seconds | Silent | Normal operation: Normal operation: the SM210L’s power LED flashes green once every minute and the horn is silent. |
| Three red flashes | Full alarm, three beeps then a pause, repeating | Real alarm: Smoke is detected. |
| Three red flashes | Silent | Hush or silence mode: Silence mode: after the Test/Silence button is pressed during an unwanted alarm, the horn is quiet for up to 8 minutes while the red LED repeats three flashes and a pause. |
| Three green flashes about every 60 seconds | Three chirps about every 60 seconds | Fault: Malfunction signal: the alarm is not working properly and needs to be replaced. |
| One green flash about every 60 seconds | Five chirps about every 60 seconds | Low battery: Low battery signal. |
| Five green flashes about every 60 seconds | Five chirps about every 60 seconds | End of life: End of life: the alarm needs to be replaced. |
| Two green flashes about every 60 seconds | Silent | Fault: The alarm needs cleaning. |
Sources
First Alert’s own documents only, read on the date shown.
- First Alert (BRK Brands): User’s Manual — Smoke Alarm, 10-Year Sealed Battery with Escape Light — Model SM210L. support.firstalert.com Checked 2026-09-29.
- First Alert: Why Is My Smoke Detector Beeping (Safety Corner) — First Alert smoke alarms (general article). www.firstalert.com Checked 2026-09-29.