How much does it cost to fix boiler error code S.46?

Typical repair cost for the boiler S.46 fault is £80-220 including labour.

S.46 Medium

Boiler Fault Code S.46

Also written as S46 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 31 August 2026

Fault code S.46 appears across 2 boiler brands and 31 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has noticed an unstable flame when running at its lowest setting and is operating at a restricted level to prevent a complete breakdown. (As reported on Vaillant ecoTEC pro)

Pick your boiler brand for the S.46 fix

Glow-worm S.46 20 models Vaillant S.46 11 models

Source

Information for the S.46 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