Boiler Fault Code 63:15

Also written as 6315 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026

Fault code 63:15 appears across 1 boiler brand and 5 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has detected an internal electronic error that suggests the main control unit is beginning to fail, which may cause your heating and hot water to become unreliable. (As reported on Viessmann Vitodens 200)