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Navien NFC-250/200H Error Codes

Updated · by Aurora Star Tech Inc.

Navien NFC-250/200H error codes and diagnostic codes. The NFC-250/200H is a Navien combi boiler in the Navien NFC-H series.

Homeowner with a combi boiler problem? Call (647) 657-2977 or book a service call — licensed technicians across Vaughan and the GTA.

Navien NFC-250/200H error codes list

CodeMeaningSeverity
E001Heat exchanger overheatHigh
E003Ignition failureHigh
E004False flame detectedHigh
E012Flame lossHigh
E016Heat exchanger overheat (overheating of heat exchanger)High
E030Exhaust overheat (abnormal exhaust temperature)High
E031Burner overheatHigh
E046Heat exchanger thermistor / overheat sensor faultMedium
E047Exhaust thermistor faultMedium
E060Dual venturi faultMedium
E109Fan motor faultHigh
E110Exhaust blockage / abnormal air pressure (APS)High
E205Heating supply temperature sensor faultMedium
E218Heating return temperature sensor faultMedium
E278External (system) supply sensor not detectedMedium
E279External (system) return sensor not detectedMedium
E302Low water pressure (internal LWCO)High
E351Auto feeder (make-up water) valve faultHigh
E352High water pressureHigh
E353Water pressure sensor faultMedium
E407DHW outlet temperature sensor faultMedium
E421DHW cold water inlet sensor faultMedium
E434Water adjustment (flow control) valve faultMedium
E439No DHW flow detected / flow sensor faultMedium
E441DHW outlet 2 sensor faultMedium
E445Mixing (bypass) valve faultMedium
E515PCB faultHigh
E517DIP switch setting faultMedium
E594EEPROM faultMedium
E615Memory fault (input and memory)Medium
E736Cascade communication faultMedium
E740Outdoor sensor not detectedLow
E761Pump aquastat (pre-heat aquastat) not detectedLow
E762Vent pipe not fully inserted (VID)Critical
E773Improper gas type detectedCritical
E777Low water cutoff (LWCO) activatedHigh
E782Front panel communication faultMedium
E784Zone controller communication faultLow
E786Improper front panelMedium
E788Incorrect gas type settingCritical

Troubleshooting the NFC-250/200H

Navien NFC-250/200H specs and setup data

All Navien Combi Boiler error codes →

Homeowner help: Tankless Water Heater No Hot Water: What to Check · Boiler Not Heating: What to Check

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.

© 2026 Aurora Star Tech Inc. All rights reserved. This page may not be copied, republished or used to train other systems without written permission.

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