004Error - Navien NCB-180 Service Manual

5.2.2 004Error

Error occurrence conditions and check items
Error
1. Pre ignition false-flame
If a flame signal is detected continuously for 3 seconds before combustion (stand-by, pre-purge, pre-
ignition), a false-flame error 004E (automatically cleared) is displayed on the front panel and the system
performs continuous post-purge and operates the pump.
E004
False-flame
detection
2. Post purge false-flame
If a flame signal is detected continuously for 3 seconds when the system performs post-purge as fuel
supply is stopped, a false-flame error 004E (automatically cleared) is displayed on the front panel and the
system performs continuous post-purge and operates the pump.
1. Check if gas leaks due to defective seals on the main gas valve.
2. Check if proper spark is discharged from the electrode.
Check items
3. Check if gas is supplied within the proper pressure range.
4. Check the PCB and replace if defective.
Check method
Failure mode
Flame
Leakage from
before/after
main gas valve
combustion
Discharge of
electricity from
electrode
Error before/after
combustion
Gas valve
Other trouble Defective PCB
86 NCB Service Manual
Is the flame detected in
the burner when there
is no ignition?
YES
External noise current
Cause
Replace the gas flame if flame occurs before combustion or if there is remaining flame
after combustion is stopped.
Spark discharges from electrode to flame sensor at ignition.
Replace or correct location of flame detecting rod.

Gas may leak as the main gas valve is pushed by the gas supply over the standard
pressure.
Check the supply pressure: NG: 3.5" ~ 10.5" WC, LP: 8.0" ~ 13.0"W.C

If the gas pressure is too high, notify the gas supplier about the issue, and if

necessary, replace the gas valve.
If there is a gas leak close the gas supply valve and repair the unit before using

the system.
If the issue continues despite the checking of items above, replace the PCB.
Description
NO
Clean or replace flame rod
Check the current #1 of CN 2: 1 - 20μA
(see page 56 for Wiring Diagram)
Check method
Version 1.0