Overheat Thermostat High

Boiler Fault Code Overheat Thermostat

Also written as OVERHEATTHERMOSTAT — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code Overheat Thermostat appears across 6 boiler brands and 18 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has automatically turned itself off because it became too hot, often caused by a build-up of air in the system or a circulation problem. (As reported on Potterton Prima 30B)

Pick your boiler brand for the Overheat Thermostat fix

Alpha Overheat Thermostat 1 model Ariston Overheat Thermostat 3 models Grant Overheat Thermostat 9 models Halstead Overheat Thermostat 1 model Ideal Overheat Thermostat 2 models Potterton Overheat Thermostat 2 models

Source

Information for the Overheat Thermostat 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