What error codes indicate a system malfunction on the Infinity Thermostat?

Several error codes will generate a 'System Malfunction' message. For fan coils, these include Code 37 (heater output sensed on when not energized), Code 41 (blower motor fault), Code 44 (motor communication fault), and Code 45 (control failure). For furnaces, critical codes include Code 13 (limit circuit lockout), Code 14 (ignition lockout), Code 15 (blower motor lockout), and Code 41 (blower motor fault in cooling mode). When a system malfunction occurs, check the Last 10 System Events screen in the Service Menu to determine which fault caused the message.