Navien NFB-200H Error Codes

Updated October 13, 2026 · by Aurora Star Tech Inc.

Navien NFB-200H error codes and diagnostic codes (also listed as NFB200H). The NFB-200H is a Navien boiler in the Navien NFB-H series.

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Navien NFB-200H error codes list

Code	Meaning	Severity
E001	Heat exchanger overheat	High
E003	Ignition failure	High
E004	False flame detected	High
E012	Flame loss	High
E016	Heat exchanger overheat (check flow / system filters)	High
E030	Exhaust overheat	High
E031	Burner overheat	High
E046	Heat exchanger thermistor fault	Medium
E047	Exhaust thermistor fault	Medium
E060	Dual venturi fault	Medium
E109	Fan motor fault	High
E110	Exhaust blockage	High
E205	Heating supply temperature sensor	Medium
E218	Heating return temperature sensor	Medium
E278	External system supply sensor not detected	Medium
E279	External system return sensor not detected	Medium
E291	Return temperature higher than supply	Medium
E302	Low water pressure	High
E352	High water pressure	High
E353	Water pressure sensor fault	Medium
E480	DHW tank sensor not detected	Low
E515	PCB fault	Medium
E517	DIP switch setting fault	Medium
E594	EEPROM fault	Medium
E615	Memory fault	Medium
E736	Cascade communication fault	Medium
E740	Outdoor sensor not detected	Medium
E762	Vent pipe not fully inserted (VID)	Critical
E777	Low water cutoff activated	High
E782	Front panel communication fault	Medium
E784	Zone controller communication fault	Medium
E786	Improper front panel detected	Medium
E788	Incorrect gas type setting	High

Troubleshooting the NFB-200H

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General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.

Navien NFB-200H error codes list

Troubleshooting the NFB-200H

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