Navien NFC-175, Service Manual

Page: 103 / 138

NFC Service Manual 103 Version 1.0
5.2.18 351Error
Error Condition and Check Items
Error Description
E351 Abnormal Auto feeder valve
Check Items
1. Check for leaks within the boiler interior.
●
Leaks disrupt from securing target pressure.
2. Check pressure in direct water supply valve connection.
●
Errors occur if water does not enter during the water supply function. Check if exterior
direct water supply valves are open.
3. Check auto feeder valve harness.
●
If the problem persists after completing (1) and (2) check with circuit tester whether
there is a disconnection between harness sockets.
4. Change auto feeder valve
●
If the problem persists after completing (1), (2), and (3), change the auto feeder valve.
5. Check panel pressure.
●
If the problem persists after completing (1), (2), (3), and (4) check the panel pressure to
check whether the pressure sensor is working properly.
6. Check pressure sensor harness.
●
Check for pressure sensor harness disconnection if unable to check panel pressure.
7. Change pressure sensor
●
If the problem persists after completing (6) change the pressure sensor.
8. Change PCB
●
If the problem persists after completing all the actions above, change the PCB.
Water supply
valve
water supply valve connector