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Navien NPE-150S2 Error Codes

Updated · by Aurora Star Tech Inc.

Navien NPE-150S2 error codes and diagnostic codes (also listed as NPE150S2). The NPE-150S2 is a Navien tankless water heater in the Navien NPE-2 series.

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

Navien NPE-150S2 error codes list

CodeMeaningSeverity
E003Ignition failureHigh
E004False flame detectionMedium
E012Flame lossHigh
E016Heat exchanger overheatingHigh
E030Exhaust overheatingHigh
E031Burner overheatingCritical
E046Limit control abnormalHigh
E047Exhaust thermistor open or shortedMedium
E060Dual venturi abnormalHigh
E21No hot waterMedium
E109Fan motor abnormalHigh
E110Abnormal air pressureHigh
E407Hot water outlet thermistor open or shortedMedium
E421Cold water inlet 1 thermistor open or shortedMedium
E432Cold water inlet 2 thermistor open or shortedMedium
E434Water adjustment valve abnormalMedium
E438Circulation pump abnormal (with air handler)Medium
E439Flow sensor abnormalMedium
E441Hot water inlet 2 thermistor open or shortedMedium
E445Bypass mixing valve abnormalMedium
E515PCB abnormalHigh
E517DIP switch setting abnormalMedium
E593Front panel key abnormalLow
E594EEPROM abnormalHigh
E615Input and memory abnormalHigh
E736Cascade communication abnormalMedium
E740Outdoor temperature sensor abnormal (with air handler)Low
E760Flushing / service alarmLow
E762Vent pipe not properly insertedHigh
E773Wrong gas type detectedCritical
E782Main / panel communication abnormalMedium
E785Flow switch / sensor abnormal (with air handler)Medium
E788Gas type mismatch: DIP switch vs panel settingMedium

Troubleshooting the NPE-150S2

Navien NPE-150S2 specs and setup data

All Navien Tankless Water Heater error codes →

Homeowner help: Tankless Water Heater No Hot Water: 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.

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