BoilerFaultCodes 394 High
Boiler Fault Code 394
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 394 appears across 2 boiler brands and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning The boiler has lost the signal from a sensor that monitors the temperature of the hot exhaust gases leaving through the flue, so it has likely shut itself down as a safety precaution. (As reported on Viessmann Vitodens 050-W B0HA-19)
Pick your boiler brand for the 394 fix
Source
Information for the 394 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 31 August 2026