How much does it cost to fix boiler error code F.406?

Typical repair cost for the boiler F.406 fault is £150-300 including labour.

F.406 High

Boiler Fault Code F.406

Also written as F406 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code F.406 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 detected an issue with the flame sensing system, preventing it from safely lighting and maintaining a burner flame. (As reported on Viessmann Vitodens 100-W WB1A)

Pick your boiler brand for the F.406 fix

Viessmann F.406 4 models

Source

Information for the F.406 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