BoilerFaultCodes ALL 84 High
Boiler Fault Code ALL 84
Also written as ALL84 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code ALL 84 appears across 1 boiler brand and 3 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 it is not receiving enough gas to operate safely and has shut itself down to prevent damage. (As reported on Sime Brava Slim HE Regular)
Pick your boiler brand for the ALL 84 fix
Source
Information for the ALL 84 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