BoilerFaultCodesYour boiler has detected an unusual temperature difference between its sensors and has shut down to prevent any internal damage.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Sensor control protection activation
What causes this fault?
This fault occurs when the boiler detects a conflicting temperature reading between its internal flow and return pipes. It usually happens because water isn't moving through the unit fast enough, or because one of the temperature sensors has become inaccurate or faulty. The boiler shuts down as a safety measure to prevent the heat exchanger from overheating due to this poor circulation.
This fault is more frequent in winter when heating systems are under high demand, as sludge or debris in the radiators can more easily restrict the water flow required for the boiler to operate safely.
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 F42 — no call-out fees, no surprises.
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