BoilerFaultCodes AL 09 High
Boiler Fault Code AL 09
Also written as AL09 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code AL 09 appears across 1 boiler brand and 14 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 water is not moving around the system properly, which is preventing the unit from heating up safely. (As reported on Sime Murelle Pro HE 25 HO)
Pick your boiler brand for the AL 09 fix
Source
Information for the AL 09 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