Troubleshoot false smoke alarms or when the app says "the smoke sensor has failed"

If Google Nest Protect sounds a smoke alarm when there is no smoke, or if it chirps and your Nest app says there’s a sensor failure, then it needs your attention. In some cases, this occurs because dust got into the smoke chamber or steam has set it off. Dusting your Nest Protect and placing it away from any sources of steam can solve the issue.


Dusting your Nest Protect

All photoelectric smoke alarms can be impacted by dust. So it’s
important to keep your Nest Protect free of dust during the
installation process and to clean it if dust is building up. Nest
Protect constantly monitors its sensors, to ensure that they’re
working properly, so if dust interferes with the smoke sensor
Nest Protect can let you know. But it’s still important to keep an
eye out for dust build-up to help keep your Nest Protect clean
and working properly.

There are two signs that dust may have made it into the smoke chamber:

  • Nest Protect begins to chirp and the Nest app says “The
    smoke sensor has failed”.
  • Nest Protect sounds a Heads Up or Emergency Alarm saying
    there’s smoke, even though there isn’t.

Learn more about Nightly Promise >

app protect smoke sensor failure


Nest takes steps during the manufacturing process to ensure that your Nest Protect remains dust-free. We also package it with a dust cap to keep dust out during the shipping process.

However, dust can get into your Nest Protect in several
 ways. For example, removing the old smoke alarm during
installation can stir up dust. This is especially true with
wired Protects which have wires running through the
wall or ceiling. Dust can also accumulate on your Nest
Protect over time, like it can on your furniture and other
appliances in your home.

You’ll want to give Nest Protect a thorough dusting, and
see if that solves the problem. You can find out how to
dust your Nest Protect here:

How to clean my Nest Protect >

If the problem persists, please contact Nest Support.

Nest Protect dust cap removal

Placing Nest Protect away from sources of steam

Steam can also trigger false alarms in many smoke alarms. Common household sources of steam include showers and humidifiers. So if you’ve experienced a false alarm and your Nest Protect is placed nearby a source of steam, this may well be the cause.

To help lower the number of false alarms caused by steam, Nest developed Steam Check. Steam Check helps Nest Protect tell the difference between steam-related events and real fire or smoke events.

Learn more about Steam Check >

While Steam Check helps Nest Protect distinguish between steam and smoke, but it won't stop all steam-related alarms. If Nest Protect observes steam that appears similar to real smoke or fire, the alarm will sound.

Steam Check helps lower the number of false alarms caused by steam or high humidity, but the best way to eliminate steam-related false alarms completely is to move Nest Protect away from sources of steam like bathrooms and home humidifiers.

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