BoilerFaultCodesYour boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, causing it to shut down as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Wiring or resistance issues with the Flow Thermistor located in the flow pipe (upper RHS of boiler).
What causes this fault?
This fault occurs when the internal sensor responsible for measuring the heat of the water leaving your boiler fails or sends an incorrect signal to the control board. The most common reason is that the sensor's internal electrical resistance has drifted out of range due to age, or the wiring connecting it to the main computer has become loose or damaged.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like Flow Thermistor Fault — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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