BoilerFaultCodesYour boiler has sensed that the water returning from your radiators is hotter than the water leaving the boiler, which usually means there is a circulation problem or a sensor fault.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Return sensor temperature > flow sensor temperature.
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the system is operating in reverse, with the return pipe being hotter than the flow pipe. The most common reason is a circulation failure, often caused by a faulty pump or a blockage in the heat exchanger that prevents water from moving through the boiler correctly. It can also be triggered if one of the temperature sensors has failed and is providing an incorrect reading to the control board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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