Navien NCB-180, Service Manual

Page: 114 / 149

Check method
Fault Possible Causes Check method
Defective sensor
Defective
temperature sensor
connector
Check if the temperature sensor is open and if the connector is connected properly.
Temperature sensor
Check the resistance of the temperature sensor. (Defective if it is 30kΩ or higher)

Replace the temperature sensor if the resistance value is abnormal.
(refer to page 62)

Check the temperature displayed on the front panel.
(refer to page 39
Possible Issues
Defective PCB
If the issues continue despite checking the items above, replace the PCB.
<DHW Flow sensor input temperature sensor / connector>
Check if the hot water temperature sensor is open (Error type : MΩ Open)