63 High

Boiler Fault Code 63

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 63 appears across 4 boiler brands and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has automatically shut down because the exhaust gases have reached a temperature that is too high, which is a safety feature to prevent damage or dangerous operation. (As reported on Viessmann Vitodens 100-W B1GA)

Pick your boiler brand for the 63 fix

Baxi 63 1 model Ideal 63 1 model Sime 63 4 models Viessmann 63 1 model

Source

Information for the 63 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →

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