What do the different alert codes mean and what should I do about them?

The T6 Pro displays 3-digit alert codes when issues occur. For example, code 164 indicates Heat Pump Needs Service, code 181 means Replace Air Filter, and code 400 means No WiFi Signal. When you see the alert symbol on the thermostat screen, touch Menu to access the ALERTS sub-menu where you can view the specific code and description. The manual provides a complete chart of all alert codes and recommended actions on page 27.