BoilerFaultCodes 545 Medium
Boiler Fault Code 545
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 545 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 a faulty connection in a temperature sensor for a secondary heating zone, so it has stopped that zone from heating to prevent potential damage. (As reported on Viessmann Vitodens 100-W B1GA)
Pick your boiler brand for the 545 fix
Source
Information for the 545 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