High Lockout
401 on Ideal Ideal Classic SE15P FF

Your boiler's internal computer brain has experienced a malfunction and can no longer communicate with the heating system.

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

internal failure - electronic

What causes this fault?

This fault occurs when the boiler's central control board suffers a hardware failure, meaning it can no longer process instructions or monitor safety sensors. The most common reason is an electrical short-circuit or component degradation on the circuit board that prevents it from 'thinking' correctly. Because the control board is the brain of the appliance, it shuts down completely for safety when it detects this internal error.

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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