b7 High

Boiler Fault Code b7

Also written as B7 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code b7 appears across 2 boiler brands and 16 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's internal computer chip has been disconnected or has developed a communication fault, meaning the system doesn't know which settings to use. (As reported on Viessmann Vitodens 200)

Pick your boiler brand for the b7 fix

Viessmann b7 8 models Worcester Bosch b7 8 models

Source

Information for the b7 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