Navien NP-180 Service Manual page 82

Check method
Error type
Defective
temperature
sensor connector
Sensor error
Temperature
sensor
Defective
Other trouble
©Navien America Inc. 2010
Cause
Check if the hot water temperature sensor connector or the PCB
harness terminal is wet due to any reason, including leakage.
Use a tester to measure the temperature sensor resistance.
If the resistance is abnormal, replace the temperature sensor
(abnormal if it is lower than 0.5 ).
Check the output temperature displayed on the PCB.
(H.50.5 50.5 )
If the trouble continues despite the checking of above items,
replace the PCB.
PCB
<Hot water temperature sensor /
Red line 2P>
NR/NP series service Manual
Check method
<Check if the hot water temperature
sensor line is open>
80
Version 2.0