Wired Remote 121 — Indoor temperature sensor (open/short error)

What does 121 mean?

The wired remote controller displays error code 121, indicating an open or short circuit with the indoor unit's room temperature sensor. This sensor is crucial for accurate temperature control.

• Faulty room temperature sensor
• Loose or damaged sensor connection to the indoor PCB (CN41)
• Indoor unit PCB malfunction

Click steps to track your progress.

1. 1

   Turn off the power to the indoor unit at the circuit breaker.

2. 2

   Visually inspect the indoor unit's room temperature sensor (often a small probe or part of the front panel) for any damage.

3. 3

   Check the sensor's wiring connection to the indoor unit's PCB (connector CN41, often white) to ensure it is secure.

4. 4

   Restore power. If the error persists, contact a qualified technician to test or replace the sensor.