Understanding Error Codes - Navien NCB-24LDWE User's Information Manual

4.2 Understanding Error Codes

When an error code appears on the front panel, refer to the following chart for a definition and possible remedy for the situation.
Error Code Reason
003 Ignition failure
004 False flame detection
012 Flame loss
016 Heat exchanger overheat
030 Abnormal exhaust temperature
046 Abnormal operation: Heat exchanger overheating sensor
047 Abnormal operation: Exhaust thermostat
060 Abnormal operation: Dual venturi limit switch
109 Abnormal operation: Fan
110 Exhaust blockage (Condensate blockage)
127 Abnormal operation: APS
205 Heating supply thermistor open or short circuit
218 Heating return thermistor open or short circuit
302 Low water pressure
352 High water pressure
353 Abnormal operation: Water pressure sensor
407 Abnormal operation: Hot water outlet thermistor
421 Abnormal operation: Cold water inlet thermistor
515 Abnormal operation: Relay feedback (PCB)
517 Abnormal operation: DIP switch setting (PCB)
594 Abnormal operation: EEPROM (PCB)
615 Abnormal operation: Input and memory (MCU)
740 Abnormal operation: Outdoor temperature sensor
782 Abnormal operation: Main panel communication
If the error code is not cleared by resetting the boiler functioning (see "3.5 Resetting the Boiler") or if it occurs repeatedly, call the nearest
official Technical Assistance Service (TAS), indicating the number of the error code appearing on the front panel.
Reset
Manual reset
Auto reset
Manual reset
Manual reset
Manual reset
Auto reset
Manual reset
Auto reset
Auto reset
Manual reset
Manual reset
Manual reset
Auto reset
Alarm
Auto reset
Auto reset
Auto reset
Alarm
Auto reset
Manual reset
Manual reset
Alarm
Manual reset
Auto reset
Auto reset
Troubleshooting 15