Navien NCB500-2S/37K User Manual

84 Troubleshooting
5.2.16 Error 407
Error conditions and checklist
Error Description
E407
Hot water outlet thermistor open or short
If an error (open: -10°C or lower) in the DHW Outlet Elbow input temperature sensor is
detected, the system displays the 407E error on the front panel.
Check items
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?
Check connector
Replace the DHW outlet thermistor
No
Yes
Before measuring resistance of the
thermistor, detach the connector
from the PCB.

Navien NCB500-2S/37K Specifications

General

Brand	Navien
Model	NCB500-2S/37K
Category	Boiler
Language	English