Navien Water Heater Error Codes & Fix Guides
All FixCode Guide coverage for Navien water heater error codes: start with the complete code list, or jump to a deep-dive guide for a specific code. Everything is verified against Navien manufacturer documentation.
Guides in this section
Navien Water Heater Error Codes List: Every Code ExplainedNavien Error Code E003: Ignition Failure — Meaning, Causes & FixNavien Error Code E110: Exhaust Blockage — Meaning, Causes & FixNavien Error Code E012: Flame Loss — Meaning, Causes & FixNavien Flow, Pump & Recirculation Error Codes (421, 438, 517): Meaning & FixesNavien Fan, Sensor & Electronics Error Codes (109, 127, 762, 773): Meaning & FixesNavien Water Heater Reset: How to Reset & Clear Error Codes
Most searched Navien water heater codes
| Code | Meaning |
|---|---|
| E003 | Ignition failure — Navien tankless water heaters (NPE, NPE-2; legacy display form 003). The unit attempted ignition and no flame was detected. Navien's NPE Service Manual states the sequence exactly: in the case of an ignition failure, the water heater will attempt ignition 10 times; if no flame is detected, it displays E003, which is manually cleared. Manual reset. |
| E012 | Flame loss — Navien tankless water heaters (NPE, NPE-2; legacy display form 012). The burner ignited and flame was proved, then the flame was lost during operation. Navien's user-manual actions for E012 are to clean the intake air filter and ensure the electrical cord is properly grounded. Manual reset. |
| E110 | Exhaust blockage / abnormal air pressure — Navien tankless water heaters (NPE, NPE-2; legacy display form 110). Navien's US user manuals name E110 'abnormal air pressure'; the NPE Service Manual and the NPE AWE/SWE table name the same code 'exhaust blockage (condensate blockage)'. The Service Manual's subcodes divide it: 1 = exhaust blockage (checking the fan), 2 = exhaust blockage (using hot water), 3 = exhaust blockage (using space heating). Manual reset. |