Los Angeles Navien owners see more error codes than homeowners in most other cities — because LA's extremely hard water (200–400 mg/L) accelerates scale buildup in Navien heat exchangers. Here is a complete guide to every Navien error code we commonly see, with causes and fixes.
| Code | Meaning | Fix Guide |
|---|---|---|
| E001 | Abnormal Combustion — No Ignition | Fix Guide |
| E003 | Ignition Failure | Fix Guide |
| E010 | Exhaust/Intake Blockage | Fix Guide |
| E012 | Flame Loss During Operation | Fix Guide |
| E016 | Overheating — High Exhaust Temperature | Fix Guide |
| E027 | Scale Buildup Alert | Fix Guide |
| E028 | Recirculation Flow Sensor Fault | Fix Guide |
| E030 | Exhaust Thermistor Fault | Fix Guide |
| E036 | Cold Water Inlet Sensor Fault | Fix Guide |
| E038 | Exhaust Temperature Sensor Fault | Fix Guide |
Los Angeles tap water has among the highest mineral content in the United States — typically 200–400 mg/L of calcium and magnesium. This hard water deposits scale inside Navien heat exchangers, causing flow restrictions, overheating, and the error codes listed above.
Annual descaling prevents most Navien error codes entirely. We recommend all Los Angeles Navien owners schedule annual maintenance to clear scale before it triggers codes or causes permanent damage.
Learn More About Navien Service in LAError code on your Navien? We diagnose and repair all Navien models throughout LA — service available.
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