BoilerFaultCodes E73-355 High
Boiler Fault Code E73-355
Also written as E73355 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E73-355 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 detected that a small protective cover used for testing the flue gases is either loose, damaged, or not properly sealed, which is preventing the boiler from operating safely. (As reported on Keston Qudos 28S)
Pick your boiler brand for the E73-355 fix
Source
Information for the E73-355 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