BoilerFaultCodes AL74, AL79 High
Boiler Fault Code AL74, AL79
Also written as AL74AL79 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code AL74, AL79 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 encountered a technical communication or internal sensor error and has stopped working as a safety precaution. (As reported on Vokera Sabre 29H)
Pick your boiler brand for the AL74, AL79 fix
Source
Information for the AL74, AL79 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 27 April 2026