Google's thermostat help index directs M22 and offline conditions to network and app connection troubleshooting.
What M22 / Offline means
Google's thermostat help index directs M22 and offline conditions to network and app connection troubleshooting.
What you may notice
- The display or status light shows M22 / Offline
- The app reports the thermostat offline
- Remote changes do not reach it
- Local temperature control may continue
Most likely causes
- 01The home network is unavailable
- 02The thermostat lost power
- 03Wi-Fi credentials changed
- 04Signal strength is weak
- 05The thermostat has a network hardware fault
Safe checks, in order
Start with the simplest non-invasive check. Stop as soon as the error clears; repeated resets can hide a condition without correcting it.
Check local operation
Confirm the thermostat still controls temperature at the wall.
Check the home network
Verify another device can reach the internet on the same Wi-Fi.
Restart normally
Restart the thermostat and router without factory resetting either one.
Reconnect in the app
Use the official connection flow if the network name or password changed.
Know where to stop
Do not factory reset the thermostat until you have the equipment configuration and wiring information recorded.
When to call a technician or support
Contact support if the thermostat has power but cannot see networks, or an HVAC professional if local control is also lost.
When you call, have the exact product model, the complete code or light pattern, and when it appeared.
Where this information came from
We use the manufacturer's current published guidance as the starting point, then organize it into a safer, beginner-friendly sequence.
Google Home Help — Nest thermostat help codes Source last checked August 18, 2026. Manufacturer instructions and model manuals take priority over this independent summary.