Outside temp. sensor faulty - heating backup operation active
Remedy
1. If an outside temperature sensor is not desired. Select the room temperature dependent configuration in the control device.
2. If there is no continuity, rectify the fault.
3. Clean corroded terminals in the outside sensor housing.
4. If values do not match, replace the sensor.
5. If the sensor values matched, but the voltage values do not match, replace the control unit.