BoilerFaultCodes F.394 High
Boiler Fault Code F.394
Also written as F394 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F.394 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 disconnection in a safety sensor that monitors the exhaust temperatures, causing it to shut down to prevent unsafe operation. (As reported on Viessmann Vitodens 222-F B2TF)
Pick your boiler brand for the F.394 fix
Source
Information for the F.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 7 July 2026