S.13 High

Boiler Fault Code S.13

Also written as S13 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code S.13 appears across 3 boiler brands and 53 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is struggling to light the gas flame and is currently stuck in the ignition phase. (As reported on Glow-worm Ultracom 2 SXI)

Pick your boiler brand for the S.13 fix

Glow-worm S.13 9 models Heatline S.13 8 models Vaillant S.13 36 models

Source

Information for the S.13 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 27 April 2026