BoilerFaultCodes Safety thermostat lock out High
Boiler Fault Code Safety thermostat lock out
Also written as SAFETYTHERMOSTATLOCKOUT — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Safety thermostat lock out appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has overheated, causing it to shut down automatically for safety. (As reported on Biasi Riva Plus M96.24SM)
Pick your boiler brand for the Safety thermostat lock out fix
Source
Information for the Safety thermostat lock out 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