BoilerFaultCodesYour boiler has detected a problem with the sensor that monitors the water temperature returning from your radiators, causing the system to stop working 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: Return Thermistor Fault
What causes this fault?
This fault occurs when the internal control board loses communication with the sensor that monitors water temperature coming back from your radiators. The most common reason is that the sensor itself has failed due to age, or the electrical wiring connecting it to the main system has become loose or damaged.
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 F5 — 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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