BoilerFaultCodes F.543 Medium
Boiler Fault Code F.543
Also written as F543 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F.543 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 has detected an electrical fault in a temperature sensor that helps manage the heat distribution to your radiators or underfloor heating. (As reported on Viessmann Vitodens 100-W WB1A)
Pick your boiler brand for the F.543 fix
Source
Information for the F.543 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