BoilerFaultCodesYour boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, preventing it from heating correctly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: FLOW THERMISTOR ERROR
What causes this fault?
This fault occurs when the internal sensor responsible for measuring the temperature of the water leaving the boiler fails to send a clear signal. The most common reason is that the sensor's electrical resistance has moved out of its normal range, or the wired connection between the sensor and the main control board has become loose or corroded. Because the boiler cannot accurately tell how hot the water is, it shuts down as a safety precaution to prevent overheating.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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