BoilerFaultCodes Neon B High
Boiler Fault Code Neon B
Also written as NEONB — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Neon B appears across 1 boiler brand and 1 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 down because it detected that it was getting too hot, likely to prevent internal damage. (As reported on Alpha Cd25)
Pick your boiler brand for the Neon B fix
Source
Information for the Neon B 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