Boiler Fault Code AL 16

Also written as AL16 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026

Fault code AL 16 appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has failed to ignite properly because it cannot detect that the water is warming up, so it has shut down as a safety precaution. (As reported on Sime Ecomfort System Plus HE EV)