Medium
E787 on Navien NCB500

Your boiler has detected a minor internal software or communication glitch and needs to be restarted to clear the error.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Abnormal operation: Reset device

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.

DIY fix possible

Locate the power switch or the fuse spur supplying the boiler.Turn the boiler power off and wait for at least 60 seconds.Turn the power back on and see if the error code clears itself.

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Related fault codes

E786View →E788View →

All 52 fault codes on the NCB500

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

001003004012016030031046047109205218302352353515517593594615740782E001E003E004E012E016E030E031E046E047E109E110E205E218E291E302E351E352E353E480E515E517E593E594E598E615E740E782E783E788

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