Navien NCB-24LSWE, Service Manual

Page: 82 / 144

80 NCB Service Manual Version 1.0
Error
Code Sub
Code
Function Diagnosis/Actions
E109
0 Fan motor activity error
1. Check and clean the air intake filter.
2. Check and clean the fan motor.
3. Test the voltage from the PCB to
ensure that it is correct. Replace fan if
PCB voltage is normal.
E110
1 Exhaust blockage (fan)
1. Check the exhaust pipe for
obstructions.
2. Check and clean the intake air filter.
3. If possible, remove the exhaust pipe
to ensure that the flue is clear.
2 Exhaust blockage (DHW)
3 Exhaust blockage (space heating)
E205
1 Heating supply thermistor open error
1. Check the thermistor.
2. Check pump wiring connections. 2 Heating supply thermistor short error
E218
1 Heating return thermistor open error
Check the thermistor.
2 Heating return thermistor short error
E302
0 Low water pressure
1. Check the feeder valve.
2. Check the incoming water pressure
and activity at the PRV.
E352
0 High water pressure
1. Check the feeder valve.
2. Check the incoming water pressure
and activity at the PRV.
E353
1 Water pressure sensor open error
Check the water pressure sensor.
2 Water pressure sensor short error
E407
1 Hot water outlet thermistor open error
1. Check the thermistor.
2. Replace the thermistor. 2 Hot water outlet thermistor short error
E421
1 Cold water inlet thermistor open error
1. Check the thermistor.
2. Replace the thermistor. 2 Cold water inlet thermistor short error
E515
1-7 PCB internal communication error Check the PCB.
8 PCB to igniter communication error
1. Check the PCB connection.
2. Check the igniter.
9 PCB to fan communication error
1. Check the PCB connection.
2. Check the fan.
10 PCB monitoring device error
1. Check the PCB connection.
11-12 PCB to dual venturi communication error
1. Check the PCB connection.
2. Check the dual venturi.
13-14 PCB to 3-way valve communication error
1. Check the PCB connection.
2. Check the 3-way valve.