Boiler Fault Code Overheat Neon Illumination

Also written as OVERHEATNEONILLUMINATION — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026

Fault code Overheat Neon Illumination appears across 1 boiler brand and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has switched itself off because it has reached a temperature that is too high, and it needs to be manually reset once it has cooled down. (As reported on Baxi Solo 3 PFL)