On the covered Google Nest thermostat, M13, M20, M22, M23, M26 and the other M codes means m codes are a mix of informational messages and problems, and Google's table points each to its own article: M13 is the cold-weather no-power code, M20 is a "No power" alert, M22 means the thermostat is offline, M23 means a thermostat wire is undetected or unconfigured, M26 means it cannot connect to a Matter device, M12 means a Nest Temperature Sensor is not in a good spot, M19 is about changing thermostat batteries and M21 means it is unable to update software. First, read the full M code on the display, because the number decides which article applies.
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0 of 2 completedWhat to do first
ReversibleRead the full M code on the display, because the number decides which article applies.
Correct only the documented fault domain
ReversibleGoogle's M26 steps: the thermostat cannot reach a third-party Matter app, so check that its battery is not too low, that Wi-Fi is available, that it was first added to the Google Home app and that it is not already paired to the maximum number of third-party apps.
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What does M13, M20, M22, M23, M26 and the other M codes mean on a Google Nest thermostat?+
M codes are a mix of informational messages and problems, and Google's table points each to its own article: M13 is the cold-weather no-power code, M20 is a "No power" alert, M22 means the thermostat is offline, M23 means a thermostat wire is undetected or unconfigured, M26 means it cannot connect to a Matter device, M12 means a Nest Temperature Sensor is not in a good spot, M19 is about changing thermostat batteries and M21 means it is unable to update software.