This article highlights the different sensors and how this relates to the error code.

These sensors are located on the mainboard and each has a specific purpose. Often if there is an issue with the sensor, the display will communicate an error code starting with E.

T1: Indoor temperature sensor - reads the indoor temperature and communicates to your display. 

T2: Evaporator temperature sensor: reads the temperature of the indoor coil and if becomes too hot, the unit will automatically shut off. 

T3: Condensor temperature sensor: This sensor is located near your compressor to ensure the unit is not operating while the compressor is overheating. 

T2 & T3 sensors are safety measures in place and built-in logic to communicate to force the unit to shut down. 

T4: This is an empty spot on your mainboard, there is no logic needed. 

The below video shares each sensor location:

Please see the below articles related to error codes;

How To Read Error Codes – Genuine Comfort

E9 Condenser High Pressure Protection – Genuine Comfort