BoilerFaultCodesYour boiler has stopped working because it thinks the hot water tank is dangerously overheating due to a faulty electrical sensor.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Burner blocked. Short circuit - cylinder temperature sensor (system boiler).
What causes this fault?
This fault occurs when the electrical sensor that monitors the temperature of your hot water cylinder fails or develops a short circuit. The boiler's control board detects an impossible reading, such as an extreme spike in heat, and shuts down the burner to prevent the water tank from dangerously overheating. The most common reason is either a faulty internal thermistor within the sensor itself or damaged wiring connecting the sensor to the boiler.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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