Emergency
E030 on Navien NCB500

Your boiler has detected a potential water leak or a buildup of scale inside the main heating unit, which triggers a safety lock out to protect your home.

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.

What the manual says

Manufacturer manual

Water and/or exhaust gas leaks, or scale deposits in the heat exchanger

Shared across the NCB500 range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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

E031View →E032View →

All 52 fault codes on the NCB500

Seeing a different code? Every code this model can display, in one place.

001003004012016030031046047109205218302352353515517593594615740782E001E003E004E012E016E031E046E047E109E110E205E218E291E302E351E352E353E480E515E517E593E594E598E615E740E782E783E787E788

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