High Lockout
51 on Ideal Mexico Super CF3 40-80

Your boiler has successfully lit the small pilot flame, but the main burner is failing to ignite 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

PILOT WILL NOT STAY LIT WHEN THE GAS CONTROL VALVE KNOB IS RELEASED

What causes this fault?

This fault occurs when the boiler's internal safety sensors detect that the initial pilot light is burning correctly, but the instruction to open the main gas supply is failing. The most common reason is a mechanical failure within the gas control valve or a faulty solenoid coil that is unable to physically pull open the valve to let gas reach the main burners.

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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