Error - Navien NCB-24LSWE Service Manual

5.2.17 Error 407

Error conditions and checklist
Error
E407
Hot water outlet
thermistor open or
short
Check items
Version 1.0
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.
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
Description
NCB Service Manual 111