BoilerFaultCodes Sy High
Boiler Fault Code Sy
Also written as SY — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Sy 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 is unable to safely drain away excess water produced during operation, which has caused it to stop working to prevent internal damage. (As reported on Worcester Bosch Highflow 550 CDi)
Pick your boiler brand for the Sy fix
Source
Information for the Sy 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