Neon 4 High

Boiler Fault Code Neon 4

Also written as NEON4 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code Neon 4 appears across 3 boiler brands and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has stopped working because the main control panel is failing to send electrical power to the internal gas valve to start the heating process. (As reported on Saunier Duval Xeon 120 FF)

Pick your boiler brand for the Neon 4 fix

Baxi Neon 4 1 model Halstead Neon 4 1 model Saunier Duval Neon 4 2 models

Source

Information for the Neon 4 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