Boiler Fault Code A 08

Also written as A08 — same fault.

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

Fault code A 08 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 sensed that the water returning to it from your radiators is too hot, causing it to shut down to prevent damage to the system. (As reported on Vokera Verve)