High Lockout
405 on Ideal Ideal Classic SE15P FF

Your boiler’s internal computer has encountered a critical electronic error and can no longer control the heating system safely.

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 main control board suffers a hardware failure, meaning the electronic components can no longer communicate with each other. The most common reason is age-related wear to the circuitry or an electrical surge that has damaged the delicate microprocessors inside the unit.

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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Related fault codes

4 01View →4 06View →

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