High Lockout
413 on Ideal Response SE

Your boiler's computer control board has developed an internal electrical fault and can no longer communicate with the rest of the 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 internal computer brain suffers a hardware failure, meaning it can no longer send or receive instructions to vital components like the pump or gas valve. The most common reason is an electrical short-circuit or component degradation on the circuit board itself, which prevents the system from passing its safety checks.

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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