Display 121 — Zone 1 room temperature sensor error

What does 121 mean?

This error appears when the room thermostat is used and detects a short or open circuit with the Zone 1 indoor unit's temperature sensor.

• Faulty temperature sensor
• Wiring issue to the sensor

Click steps to track your progress.

1. 1

   Ensure the room thermostat is correctly connected and powered.

2. 2

   Check the wiring connected to the Zone 1 room temperature sensor for looseness or damage.

3. 3

   If the sensor appears faulty, it may need replacement.

4. 4

   Contact a technician for sensor or wiring diagnosis.