Navien tankless water heater code E012: Flame lost

Canadian and US models

1. A dirty intake air filter is restricting the air the burner needs.

   Clean the intake air filter on a Navien NPE water heaterYou can do this

   1. Turn the heater off with the Power button, then unplug it, or switch it off at its power switch or breaker if it is wired in, and let it cool.
      Always disconnect the power before taking the cover off.
   2. Take off the heater's front cover, as Navien's manual describes for this job.
      Touch only the air filter. Leave every other part inside the heater alone.
   3. Undo the screw that holds the intake air filter (top left inside the heater) and pull the filter assembly out.
   4. Take the filter out of its plastic holder, clean it with a toothbrush under clean running water, and let it dry completely.
   5. Put the filter back in its holder, refit it with the screw, and replace the front cover.
   6. Plug the heater back in, or switch the power back on, and turn it on. Navien recommends cleaning this filter every 3 to 4 months.

   Clear a Navien error codeYou can do this

   1. Deal with the cause first, using the checks listed for the code.
   2. On NPE-A2 and NPE-S2 models, press the Back button on the front panel. On first-generation NPE-A and NPE-S models and on indoor NPN models, press the Reset button on the front panel.
   3. If an NR-21DU remote controller is fitted, you can press its OK button once instead. On outdoor NPN models, which have no front panel, the remote is the way to reset. The remote shows RST when the error is reset.
   4. If the code comes back, stop resetting. Note the code and the model number and contact Navien technical support or a licensed technician.
      Resetting over and over can hide a fault that needs a technician.

2. The heater's power cord or the outlet it plugs into is not properly grounded.

   Check a Navien water heater's power cord is groundedYou can do this

   1. Find where the heater's power cord plugs in. If the heater has a plug, it should be a three-prong (grounded) plug that goes straight into a grounded outlet.
   2. Check the plug still has its ground prong, is not plugged in through a two-prong adapter or an extension cord, and that the cord is not damaged or modified.
   3. If you are not sure the outlet is grounded, or the heater is wired in with no plug, have a licensed electrician check the grounding.
      Do not open the heater or the outlet yourself.

   Same check as above: Clear a Navien error code

3. A fault in the gas, air or flame sensing system that needs a technician. Suspect this when the code keeps coming back after the checks above.

   Book a licensed gas technician

US models

1. A dirty intake air filter is restricting the air the burner needs. The NPN manual lists cleaning it but gives no steps for this model, so have a technician do it.

   Book a licensed gas technician

2. The heater's power cord or the outlet it plugs into is not properly grounded.

   Same check as above: Check a Navien water heater's power cord is grounded

   Same check as above: Clear a Navien error code

3. The heater's gas manifold or its gas type DIP switch setting does not match the type of gas supplied.

   Book a licensed gas technician

4. A fault in the gas, air or flame sensing system that needs a technician. Suspect this when the code keeps coming back after the checks above.

   Book a licensed gas technician

Booking a licensed gas technician