BoilerFaultCodesYour boiler has lost connection with its internal thermometer, meaning it cannot safely tell how hot the water is and has shut down as a precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Interruption: Flow sensor - Flow temperature sensor defective or not connected
What causes this fault?
This fault occurs when the boiler's control board can no longer detect a signal from the sensor that monitors the temperature of the water leaving the unit. The most common cause is a failure of the internal thermistor itself, though it can also be triggered by loose or corroded electrical connections within the boiler's internal wiring.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like F.00 — 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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