Ignition failure: the burner did not light.
Navien E003 on the NPE-2 user's chart is ignition failure. The owner action is to make sure the main gas supply valve is open. E004 is false flame, and its action is a grounded cord. E012 is flame loss after the burner had lit, and that row adds the intake-air filter.
Likely causes
- Main gas supply valve closed
Safe checks for E003
- Make sure the main gas supply valve is open
- If the code remains, press the Back button on the front panel once to reset, then try a hot-water tap again
Capacitors can hold a charge after the power is off. Safety terms.
When to call a pro
If E003 returns with the gas supply open, stop resetting it and call a licensed technician or Navien Technical Support at 1-800-519-8794. Gas pressure, the igniter and the gas valve are not owner checks in this chart.
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