What do the alert codes on the Honeywell T6 thermostat mean?

Alert codes provide important information about your thermostat and system status. For example, alert code 181 means 'Replace Air Filter,' code 171 means 'Set the Date and Time,' code 168 means 'WiFi Radio Error,' and code 175 means 'AC Power Resumed.' When you see the alert symbol on the thermostat home screen, touch Menu to access the ALERTS sub-menu. Touch Select to view the alert information, which will display the 3-digit code and a description. Non-critical alerts can be snoozed for up to 7 days or dismissed by touching the corresponding button.