Navien NCB-150E Service Manual page 124

Check method
Fault
Defective temperature
Defective sensor
Temperature sensor
Possible Issues
Possible Causes
Check if the temperature sensor is open and if the connector is connected
sensor connector properly.
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 18)
Check the temperature displayed on the front panel. (refer to page 18)
●
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)>
Check method
Troubleshooting 123