39 / E39
Indicates the control board may need to be replaced
This code typically points to
- Thermistors inoperable or improperly connected
- Faulty control board
Next checks to confirm
- Check connection to thermistors
- Repair/replace if needed
- Replace control board if necessary
Escalation
Outdoor fault indication
Reset behavior
Clears after thermistor/board fault is corrected.
Urgent
Fix now