How much does it cost to fix boiler error code F.404?

Typical repair cost for the boiler F.404 fault is £150-300 including labour.

F.404 High

Boiler Fault Code F.404

Also written as F404 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code F.404 appears across 1 boiler brand and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has stopped working because it cannot detect the flame required to heat your home, likely due to a loose wire or a faulty sensor signal. (As reported on Viessmann Vitodens 100-W WB1A)

Pick your boiler brand for the F.404 fix

Viessmann F.404 4 models

Source

Information for the F.404 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