BoilerFaultCodes ALL08 High
Boiler Fault Code ALL08
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code ALL08 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 an internal electronic error or a serious combustion issue that requires a professional inspection to fix. (As reported on Sime iQE Simplicity 20T)
Pick your boiler brand for the ALL08 fix
Source
Information for the ALL08 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