Boiler Fault Code 64

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026

Fault code 64 appears across 2 boiler brands and 17 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning The boiler's flame has gone out unexpectedly while starting up or running, so it has shut itself down as a safety measure and may not be providing heating or hot water until it is checked. (As reported on Viessmann Vitodens 050-W B0HA-19)