High
E003 on Navien NCB

Your boiler is failing to light the flame properly, so it has stopped trying to prevent gas from building up inside.

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

E004View →E005View →

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