Emergency
E12 on Navien NCB 28 HE

Your boiler has detected a potential issue with the gas supply or the internal gas valve, and to keep you safe, it has automatically locked itself to prevent operation.

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

Gas leak (optional)

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

E13View →

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