Navien E003 Code. Navien error code e003 indicates a failure in the ignition of the unit. Your tankless unit will throw this error message due to the.

As the winter settled in, we started using a lot of gas around the house (i.e., oven,. Up to 15% cash back navien error code e003 indicates a failure in the ignition of the unit. 110v dc to gas valve.