High Lockout
441 on Ideal Response SE

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 it can no longer send or receive instructions to vital components like the gas valve or pump. It is usually caused by electrical component degradation over time or a sudden power surge that damages the delicate circuitry on the PCB.

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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