BoilerFaultCodesYour boiler is unable to regulate its internal temperature correctly, causing the fan to run at full power even though the heating won't start.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Central Heating NTC Sensor fault or Fan/PCB connection issue (Section D or J)
What causes this fault?
This fault occurs when the boiler's control board loses accurate temperature readings, causing it to run the fan at maximum speed as a safety precaution to prevent overheating. The most common reason is a failed thermistor sensor that has stopped sending the correct electrical signal, or a loose wiring connection between the fan and the main circuit board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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