Your boiler’s internal control board has developed a critical electronic fault and can no longer manage the heating process safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: PCB Failure
What causes this fault?
This fault occurs when the boiler's internal electronic brain suffers a hardware failure, preventing it from processing information from the sensors. The most common reason is the natural degradation of electrical components on the circuit board over time, or a sudden voltage spike that has damaged the delicate circuitry. Because the board can no longer guarantee the boiler is operating safely, it shuts the system down entirely.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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