0b High

Boiler Fault Code 0b

Also written as 0B — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 0b appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's water circulation system is experiencing a fault, which means it cannot move heat around your home efficiently. (As reported on Viessmann Vitodens)

Pick your boiler brand for the 0b fix

Viessmann 0b 1 model

Source

Information for the 0b 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 27 April 2026