BoilerFaultCodes
Navien Boiler Fault Codes
675 fault codes across 9 Navien boiler models — explained in plain English.
Korean manufacturer known for high-efficiency condensing combi boilers.
Just want the most common Navien problems?
The top 8 faults across the whole Navien range — causes, DIY checks, repair costs.
High-severity Navien fault codes
E01 E121 E351 762 E762
Your boiler has failed to light the flame properly, meaning it cannot produce heat or hot water.
NCB 28 HE
Your boiler has stopped because its internal sensors have detected that the water inside the system is not circulating correctly.
NCB 28 HE
Your boiler has been trying to refill its internal water supply for too long but has failed to reach the required level.
NCB 28 HE
Your boiler has detected that the flue pipe responsible for safely venting exhaust gases outside has become loose or disconnected.
NCB 28 HE
Your boiler is struggling to detect the exhaust vent, likely because the flue pipe is not fitted securely or is the wrong size for your home.
NCB 28 HE
All models