BoilerFaultCodes AL 74 High
Boiler Fault Code AL 74
Also written as AL74 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code AL 74 appears across 1 boiler brand and 6 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 issue with a temperature sensor that monitors the water being sent to your taps or radiators, meaning it cannot accurately gauge the water heat. (As reported on Sime Brava One HE)
Pick your boiler brand for the AL 74 fix
Source
Information for the AL 74 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