E4 — Indoor return air temperature sensor error

What does E4 mean?

The indoor unit's return air temperature sensor (T1) is malfunctioning. This sensor measures the temperature of the air entering the indoor unit.

• Faulty return air temperature sensor
• Loose or damaged wiring to the sensor
• Issue with the indoor unit's control board

Click steps to track your progress.

1. 1

   Ensure the sensor is not obstructed by dust or debris.

2. 2

   Check the wiring and connections of the return air temperature sensor.

3. 3

   If the sensor is suspected to be faulty, it may need replacement.

4. 4

   If the wiring is intact, the indoor unit's main control board might be the cause.