Daikin Altherma fault CJ-02

What it means

User interface room thermistor input is out of range.

Likely causes

1. Faulty room thermistor
2. Deviation of thermistor (higher temperature measured than actual).
3. Bad contact between sensor and pipe
4. Deviation of outlet water after backup heater thermistor (lower temperature measured than actual)
5. Deviation of thermistor (lower temperature measured than actual)
6. Incorrect refrigerant charge
7. Faulty expansion valve control
8. Faulty suction thermistor
9. Blockages in refrigerant circuit
10. Faulty discharge pipe thermistor
11. Domestic hot water tank thermistor measures a higher temperature than actual (component failure)

Where to start

1. Perform a check of the room thermistor
2. Measure the room temperature and compare to the room temperature shown on the user interface (remote controller)
3. If temperature shown on the user interface differs from the measured temperature, replace the user interface (remote controller)