BoilerFaultCodesYour boiler has shut down because it has detected an unsafe increase in internal temperature, likely caused by a sensor fault or an issue with water flow.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety temperature limiter actuated: Flow probe not connected thermally correct or defective, appliance does not shut down
What causes this fault?
This fault occurs because the boiler's internal sensors have detected that the water temperature has risen too quickly or exceeded a safe limit. It is usually caused by a lack of water flow, often due to a pump failure or a blockage, which prevents the heat from being carried away from the heat exchanger. In some cases, the sensor itself may have become detached or faulty, sending an incorrect reading to the control board.
This fault is more common in autumn when heating systems are first turned on after summer, as circulation pumps can seize due to months of inactivity.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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