BoilerFaultCodes Safety thermostat activated High
Boiler Fault Code Safety thermostat activated
Also written as SAFETYTHERMOSTATACTIVATED — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Safety thermostat activated appears across 2 boiler brands and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has switched itself off because it got too hot, which is a built-in safety feature to prevent damage or dangerous overheating. (As reported on Potterton Performa 24)
Pick your boiler brand for the Safety thermostat activated fix
Source
Information for the Safety thermostat activated 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