Your boiler's internal computer has suffered a technical failure and cannot communicate with the rest of the system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Internal failure control panel.
What causes this fault?
This fault occurs when the boiler's central brain suffers a critical hardware failure or a communication breakdown between the internal components. It is often caused by an electrical surge, moisture ingress, or simply the natural degradation of the solder joints on the circuit board over time. Because the computer can no longer send instructions to the burner or pump, the boiler shuts down as a safety precaution.
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.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 9H — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Ideal Maximiser SE is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.