High
E004 on Navien NCB

Your boiler is trying to start but cannot get the flame going, which means you currently have no heating 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

Unable to ignite the gas. Results in multiple unsuccessful ignition attempts.

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

E003View →E012View →

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