To get the most out of Google Home, choose your Help Center: U.S. Help Center, U.K Help Center, Canada Help Center, Australia Help Center

2nd-gen Nest Protect sensors

The 2nd-gen Google Nest Protect features an exclusive Split-Spectrum smoke sensor and a microphone that enables complete self-monitoring if you forget to manually test it. It also has other sensors that detect temperature, humidity, occupancy and ambient light.

Nest Protect uses information from its sensors to detect smoke or CO in your home, test itself, light your way in the dark and more.

Split-Spectrum Sensor

The Split-Spectrum Sensor uses two different kinds of light to detect smoke from a wide range of fires, including both fast-flaming and slow-smouldering fires, a first for home smoke and CO alarms.

Learn more about the Split-Spectrum Sensor

Carbon monoxide sensor

The carbon monoxide sensor detects carbon monoxide (CO), an odourless, colourless and potentially deadly gas. The CO sensor lasts for up to 10 years.

Learn more about carbon monoxide

Heat sensor

The heat sensor enables Nest Protect to detect sudden rises in temperature.

Humidity sensor

The humidity sensor enables Steam Check. This Nest Protect-exclusive feature uses an advanced software algorithm to reduce nuisance alarms caused by things like steam from your shower.

Learn more about Steam Check

Occupancy sensor

The occupancy sensor detects when you are walking under Nest Protect to turn on Pathlight and light your way in the dark. And if you have a Google Nest Learning Thermostat, the occupancy sensor also helps your system switch to Eco Temperature, so that you can save energy while you’re away.

Learn more about Pathlight

Learn more about how your thermostat can automatically switch to Eco Temperature

Ambient light sensor

The ambient light sensor tells Nest Protect when you’ve turned off the lights for the night so that it can automatically turn on Nightly Promise and Pathlight.

Learn more about Nightly Promise


The microphone enables 2nd-gen Nest Protects to test their speaker and horn each time you run a test. This feature is called Sound Check.

Learn more about Sound Check

Was this helpful?
How can we improve it?
Clear search
Close search
Google apps
Main menu
Search Help Centre