What does 3 green flashes with 3 chirps mean on a First Alert?

It is First Alert's malfunction signal: the unit has an internal fault and must be replaced.

My First Alert is flashing red and beeping. What should I do?

Flashing red with the alarm sounding is the smoke pattern: get everyone out and call 911 from outside, every time.

First Alert Smoke Alarm Blinking Red? What Each Flash Means

By Kanika Modi · Part of the smoke alarm guides · Last verified 25 Sept 2026 against First Alert official documentation · 4 sources

🚨 If the alarm is sounding (3 beeps repeated): get everyone out and call 911 from outside. This page is about lights flashing with no alarm sound.

Quick Answer: on First Alert hardwired models (like the 9120B), a red flash about once a minute is the normal battery-backup standby indicator, and a solid green light means AC power is on. A red light flashing rapidly with no sound, or three green flashes together with three chirps, means trouble.

First Alert uses its lights differently across model families, which is why blogs give contradictory answers. The rules below come from First Alert’s own manuals for the hardwired 9120 series, the most installed model family in US homes.

First Alert Light Decoder

What you see	What it means	What to do
Red flash about once a minute (9120B on battery backup)	Normal standby on DC power	Normal Nothing
Solid green	AC power is on and the unit is receiving electricity	Normal Nothing
Green off, red flashing on a hardwired model	Running on battery backup: check the breaker or the AC connector	This week Restore AC power
3 green flashes + 3 chirps	Malfunction signal	Replace The unit has a fault; replace it
Red flashing rapidly, with or without sound	Alarm condition or test mode	Evacuate Treat as smoke: get out and call 911 from outside

Model matters: check the model number printed on the back of your alarm (for example 9120, 9120B, 7020BSL), then compare against First Alert’s manual for that model at firstalert.com. The patterns above cover the hardwired 9120 family, the most common.

Questions People Ask

Why is My First Alert Smoke Alarm Blinking Red Every Minute?

On the 9120B running on battery backup, a red flash once per minute with the green LED off is the normal standby indication: the unit is powered and sensing. If the alarm should be receiving AC power, check the breaker or the wiring connector.

What Does a Solid Green Light on a First Alert Mean?

AC power is on and the alarm is receiving electricity. It is the normal indicator for hardwired models.

What Does 3 Green Flashes with 3 Chirps Mean?

That is First Alert’s malfunction signal: the unit has detected an internal fault and must be replaced. Do not try to repair it.

My First Alert is Flashing Red and Beeping. What Now?

Flashing red together with the alarm (3 beeps repeated) is the smoke alarm pattern: get everyone out and call 911 from outside, every time, even if you suspect burning food.

Sources

Retrieved 25 Sept 2026:

Why Is My Smoke Detector Beeping (First Alert)
First Alert Support: sounds and light signals (First Alert)
First Alert 9120 User Manual: LED behavior chart (via ManualsLib)
Smoke alarm guidance (NFPA)

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