BoilerFaultCodes Neon B flashing High
Boiler Fault Code Neon B flashing
Also written as NEONBFLASHING — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Neon B flashing appears across 1 boiler brand and 6 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has automatically shut itself down because it detected that it is running too hot, possibly due to trapped air or a blockage in the system. (As reported on Alpha Cd25)
Pick your boiler brand for the Neon B flashing fix
Source
Information for the Neon B flashing 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 27 April 2026