Medium
253 on Navien NCM 1130HH

Your boiler has detected a confusing startup signal due to a brief electrical glitch or an internal communication error between its main control boards.

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

253: ambiguous err cause Cause of error is ambiguous after power up. BCU or EGC-Subsystem will have reported a problem before or during power up.

From this model's manual
Verified against the Navien/Navien Ncm 1130hh installation & service 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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

250View →251View →252View →

All 77 fault codes on the NCM 1130HH

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

96979899100102114116117118121122127157158164187254257258259260261262263264265266267268269270271272273274275276277278280281282283284285286287288289290291292293294295296298299300301302303304305306307308309310311319394395396397

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