Boiler Fault Code Neon A flashing

Also written as NEONAFLASHING — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026

Fault code Neon A flashing appears across 1 boiler brand and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has lost the ability to accurately measure its own internal temperature, which causes it to shut down to prevent the system from getting too hot. (As reported on Alpha CD S)