Boiler Fault Code ALL 08

Also written as ALL08 — same fault.

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

Fault code ALL 08 appears across 1 boiler brand and 8 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is failing to light because it cannot detect a flame, so it has shut down as a safety precaution to prevent a gas build-up. (As reported on Sime Murelle Elite HE Combi)