cause : Temperature sensor fault comes when evaluating the temperature sensor, an error occurred due to wire breakage or sensor not connected or measured resistance too low.

Alarm value (r2124, interpret decimal):

1: Wire breakage or sensor not connected (KTY: R > 2120 Ohm).
2: Measured resistance too low (PTC: R < 20 Ohm, KTY: R < 50 Ohm

- make sure that the sensor is connected correctly.
- replace the sensor.