Navien NCB-150E Service Manual page 86

Error Code Sub Code
Abnormal input data from High limit switch of
0
Heat exchanger
1 Abnormal input data from exhaust sensor
2 Abnormal input data from flame rod
E615
3-14 Abnormal memory of PCB
Below the range of input data from Pressure
15
sensor
Over the range of input data from Pressure
16
sensor
Abnormal outdoor temperature sensor (Open)
1 (appears only when the outdoor reset curve is
enabled).
E740
Abnormal outdoor temperature sensor (Short)
2 (appears only when the outdoor reset curve is
enabled).
E777 0 Abnormal operation: LWCO
E782 0 Abnormal Main-Panel communication
If any of the above solutions do not resolve the problem with the Boiler, contact Navien's Technical department at 1-800-519-8794.
There will be error codes displayed on the front panel and recorded on the PCB board (within the unit) of any problems or failures that occur
with the Boiler.
IMPORTANT
To reset the Boiler, either press the [Reset] button on the front panel or disconnect, then reconnect electrical power to the boiler.
Function
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1. Ensure that the outdoor reset curve is configured properly.
2. Check the outdoor temperature sensor wiring connection.
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Self-diagnostic/Action
Check the HTL and connection.
Check the PCB.
Check the exhaust sensor wiring connection
Check the exhaust sensor
Check the flame rod wiring connection.
Check the flame rod.
Check the PCB
Check the Pressure sensor wiring connection
Check the output voltage of pressure sensor
Check the LWCO wiring connection
Ensure that the system water level is appropriate.
Add make-up water to the system if necessary.
Check for proper voltage from connector(24VAC).
Check the connection between PCB and Panel
Check the PCB.
Troubleshooting 85