BoilerFaultCodes _St Medium
Boiler Fault Code _St
Also written as ST — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code _St appears across 1 boiler brand and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is currently undergoing an automatic safety shutdown process, usually because the water temperature has risen too quickly or the system is waiting for the pump to move heat away. (As reported on Vokera Mynute i)
Pick your boiler brand for the _St fix
Source
Information for the _St 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