BoilerFaultCodes 407 High
Boiler Fault Code 407
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 407 appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has detected an issue with the sensor that tracks the flow of water, which is preventing the system from operating correctly. (As reported on Navien NCB H)
Pick your boiler brand for the 407 fix
Source
Information for the 407 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026