BoilerFaultCodes I.56 Low
Boiler Fault Code I.56
Also written as I56 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code I.56 appears across 1 boiler brand and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is currently receiving a signal from an external controller, such as a smart thermostat or a building management system, asking it to provide heating or hot water. (As reported on Viessmann Vitodens 222-F B2TF)
Pick your boiler brand for the I.56 fix
Source
Information for the I.56 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 7 July 2026