The CH02 or E1 codes occur when auto-stop protection is activated. This may happen due to a short circuit in the indoor pipe sensor. In this case, a professional help is needed.
CH-02 indicates an indoor pipe sensor or outdoor sensor assembly issue. Also, there may have been a disconnection or short circuit in the system. In this case, resistance needs to be checked (10kOhm/25C for air sensor, 5kOhm/25C for pipe sensor).
kOhm at 25C. If the parameters are wrong, the sensor should be replaced.