BoilerFaultCodes 001
Error 001
Navien NCB500 Fault codes & diagnostics
52 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
System Gas 2024-present
GC Numbers 47-709-1847-709-1841-709-0941-709-0941-709-1041-709-1041-709-1141-709-1141-709-1241-709-12
Download the Navien NCB500 manual
PDF
Versions & GC numbers
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Severity at a glance
Each cell = one fault code. Hover to identify. 52 Unrated
Which version do you have?
The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.
| GC number | Appliance (register name) | Produced |
|---|---|---|
| 47-709-18 | NCB500 NCB500-1S+/30K | 2024–present |
| 47-709-18 | NCB500 NCB500-1S+/30K | 2024–present |
| 41-709-09 | NCB500 NCB500-15K System | 2024–present |
| 41-709-09 | NCB500 NCB500-15K System | 2024–present |
| 41-709-10 | NCB500 NCB500-18K System | 2024–present |
| 41-709-10 | NCB500 NCB500-18K System | 2024–present |
| 41-709-11 | NCB500 NCB500-24K System | 2024–present |
| 41-709-11 | NCB500 NCB500-24K System | 2024–present |
| 41-709-12 | NCB500 NCB500-30K System | 2024–present |
| 41-709-12 | NCB500 NCB500-30K System | 2024–present |
Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.
Just want the most common Navien NCB500 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 52 documented codes
Tap any card for details
003
Error 003
004
Error 004
012
Error 012
016
Error 016
030
Error 030
031
Error 031
046
Error 046
047
Error 047
109
Error 109
Showing 11–20 of 52
205
Error 205
218
Error 218
302
Error 302
352
Error 352
353
Error 353
515
Error 515
517
Error 517
593
Error 593
594
Error 594
615
Error 615
Showing 21–30 of 52
740
Error 740
782
Error 782
E001
Overheating of heat exchanger
E003
Unable to ignite the gas; ignition failure
E004
Unable to ignite the gas; ignition failure
E012
Unable to ignite the gas; ignition failure
E016
Unable to detect high water temperature conditions if the switch malfunctions
E030
Water and/or exhaust gas leaks, or scale deposits in the heat exchanger
E031
Burner overheat
E046
Unable to detect high water temperature conditions if the switch malfunctions
Showing 31–40 of 52
E047
Inaccurate water temperatures from inside the boiler
E109
Fan speed failure, fan assembly screw loose/disassembled, or disconnected/defective fan connection
E110
Fan speed failure, fan assembly screw loose/disassembled, or disconnected/defective fan connection
E205
Inaccurate water temperatures from inside the boiler
E218
Inaccurate water temperatures from inside the boiler
E291
Supply/Return inversion limit
E302
Low water pressure
E351
Abnormal operation: Water pressure sensor
E352
High water pressure
E353
Abnormal operation: Water pressure sensor
Showing 41–50 of 52
E480
External tank thermistor open error / External tank thermistor short error
E515
PCB malfunction
E517
Abnormal operation: DIP switch setting (PCB)
E593
Abnormal operation: Touch IC (Panel PCB)
E594
Abnormal operation: EEPROM (PCB)
E598
Abnormal operation: Panel real time clock
E615
PCB malfunction
E740
Abnormal operation: Outdoor temperature sensor
E782
Abnormal operation: Main panel communication
E783
Abnormal operation: OpenTherm remote control
Showing 51–52 of 52
E787
Abnormal operation: Reset device
E788
Error code that appears if you try to change the gas type on the front panel
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