BoilerFaultCodesYour boiler has stopped running because an external safety thermostat has detected that the water temperature has become too hot.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Optional thermostat intervention
What causes this fault?
This fault occurs when an external safety device triggers to prevent the system from getting dangerously hot. It usually happens because water is not moving through the boiler quickly enough, often due to a pump failure or a blockage in the heating pipes. When the heat cannot be carried away from the boiler, the temperature spikes and the safety thermostat cuts the power to prevent damage.
This issue is more frequent during the first cold spell of autumn when a pump that has been idle all summer fails to start up again.
DIY fix possible
Check that your pump is running and hasn't seizedEnsure all radiator valves and boiler service valves are fully openPress the 'Reset' button on the front of the boiler control panel
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