407Error - Navien NCB-180 Service Manual

5.2.16 407Error

Error conditions and Check Items
Error
E407
Hot water outlet
thermistor open or
short
Check items
108 NCB Service Manual
If an error (open: 14°F (-10°C) or lower) in the DHW Outlet Elbow input temperature sensor is detected,
the system displays the 407E error on the front panel.
1. Check if the hot water temperature sensor connector is wet due to any reason and if the connector is
connected properly..
2. Check if the temperature sensor is open or short
Is the DHW outlet
thermistor normal?
Yes
Check connector
(#5 and #6 of CN 13)
Description
NO
Replace the DHW outlet
thermistor
Resistance between #5 and #6 of CN13 is from
0.437kΩ to 176kΩ at normal condition.
(see page56 for Wiring Diagram)
Before measuring resistance of the thermistor,
detach the connector from the PCB.
Version 1.0