High
E351 on Navien NCB 35 HE

Your boiler has been trying to refill its internal water supply for too long but has failed to reach the required level.

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

The water replenishment is not completed after 5 minutes

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

E352View →E353View →

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