High Lockout
E10 on Potterton Envoy 30

Your boiler's main internal computer has developed a 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 control board fault

What causes this fault?

This fault occurs when the boiler's internal computer chips or electrical circuits suffer a hardware failure, often due to age or heat stress over time. The most common reason is that a component on the control board has burnt out or lost its ability to process data, meaning the boiler can no longer safely manage the ignition or heating process.

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

E12View →

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