BoilerFaultCodes ALL 15 High
Boiler Fault Code ALL 15
Also written as ALL15 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code ALL 15 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 stopped working because the communication wire between the main control board and the internal fan has come loose or is not properly connected. (As reported on Sime Murelle Advanced HE Combi)
Pick your boiler brand for the ALL 15 fix
Source
Information for the ALL 15 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