BoilerFaultCodesYour boiler has detected a problem with the sensor that monitors the temperature of the water used to heat your radiators, causing the system to shut down for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Central Heating flow thermistor fault.
What causes this fault?
This fault occurs when the boiler's internal computer stops receiving a reliable signal from the sensor that monitors the temperature of the water leaving the unit. The most common reason is that the sensor has physically failed due to age or internal wear, though damaged wiring or loose connections between the sensor and the main control board can also be responsible.
This fault is slightly more common in winter when the boiler is working harder and the sensor is subjected to more frequent and extreme temperature cycles.
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 F6 — no call-out fees, no surprises.
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