BoilerFaultCodes F.426 High
Boiler Fault Code F.426
Also written as F426 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F.426 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 signal error which is preventing the burner from safely igniting, meaning you currently have no heating or hot water. (As reported on Viessmann Vitodens 100-W WB1A)
Pick your boiler brand for the F.426 fix
Source
Information for the F.426 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