Emergency Lockout
F.62 on Vaillant Thermocompact

Your boiler is still detecting a flame even after it has told the gas to turn off, which is a safety conflict that causes the system to shut down.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description

Flame rectification present 4 secs. after gas valve turns off | Check gas valve, burner tubes and injectors or electronics defect

What causes this fault?

This fault occurs when the boiler's internal sensors continue to detect heat or an electrical signal from a flame even after the gas supply should have been cut off. The most common reason is a leaking gas valve that isn't closing fully, or a fault on the main circuit board that is misinterpreting signals from the burners.

Engineer required

This is a emergency 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

F.61View →F.63View →F.64View →

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