High Lockout
7L on Ideal Maximiser SE

Your boiler's internal computer has developed a fault and is unable to send the correct signals to start the heating process.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Defective control panel.

What causes this fault?

This fault occurs when the boiler's internal computer brain, known as the PCB, suffers a hardware failure or a communication breakdown between its main circuits. The most common reason is electronic component wear or a power surge that has damaged the delicate circuitry required to manage the boiler's operations.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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