BoilerFaultCodesYour boiler has detected that the sensors measuring water temperature are not reading correctly or are out of sync, 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: Flow/return temperature sensor
What causes this fault?
This fault occurs when the boiler's control board notices that the two sensors measuring water temperature are giving conflicting readings or have failed completely. The most common reason is that one of these sensors has developed a fault or become unclipped, meaning the boiler can no longer safely monitor how hot the water is getting.
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.71 — 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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