BoilerFaultCodes E03 818 High
Boiler Fault Code E03 818
Also written as E03818 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E03 818 appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has detected an issue with how it is venting waste gases, which prevents it from firing up for your safety. (As reported on Ariston Genus 27)
Pick your boiler brand for the E03 818 fix
Source
Information for the E03 818 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 7 July 2026