High Lockout
0A9 on Alpha Pro Tec Plus

Your boiler has detected an electrical fault in the system that controls the gas supply, meaning it cannot safely start up to provide heat or hot water.

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

Gas valve electrical error.

What causes this fault?

This fault occurs when the boiler's main control board loses proper electrical communication with the gas valve, which is the component responsible for releasing fuel into the burner. It is typically caused by a loose connection in the internal wiring, a moisture-related short circuit, or a mechanical failure within the gas valve's solenoid coils.

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

0A1View →0A2View →

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