Emergency
E788 on Navien NCB 35 HE

Your boiler has detected an issue with the amount of gas it is receiving or the settings used to burn it, which prevents it from operating safely.

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

Abnormal Gas Setting

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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