E121 — Indoor room temperature sensor error (Short or Open)

What does E121 mean?

The indoor unit's room temperature sensor is either short-circuited or has an open circuit, preventing accurate temperature readings.

• Indoor unit Room Thermistor Open/Short circuit
• Faulty sensor
• Loose or damaged wiring to the sensor

Click steps to track your progress.

1. 1

   Power off the indoor unit at the circuit breaker for 30 seconds, then power it back on.

2. 2

   Ensure the indoor unit's filter is clean and not obstructing airflow around the sensor.

3. 3

   If the error persists, consult a qualified technician to inspect or replace the room temperature sensor.