Excellent, just the fix I needed. Worked perfectly. Thank you very much.

Good video. I see that you still have a large oval sight glass window where the flame is checked. REPLACE THIS IMMEDIATELY! Mine blew out and the flame shot out and burned the cover panel paint off and melted the wiring harness before it shut down. HVAC company that installed it wanted $800 to repair it but since I have extensive electrical and electronic experience I did the work and saved $500. But this repair should not be attempted by anyone without that experience. Navien won't issue a recall so I've contacted consumer safety to ask them to investigate. Order a new sight glass window - it installs just like the flame igniter rod. The new one is a small circle window. Its cheap and will save you from a very expensive repair. Also this code can be caused by a dirty intake air screen. Mine had one leaf in it recently. Its in the upper left of the cabinet. If you are in there clean it as well.

Thanks for the video.. But just for your information. , servicing yourself Voids of the warranty.

Hopefully you paid a service fee to the plumber for the diagnosis?

Hey did that sort out the e012 code?

got this replaced and it's still giving me the error. so annoying

How many years did you have this before having to repair this part?

Very helpful video. On a Navien combi unit does this affect the heating system hot water or just domestic hot water? (Are they separate rod units?)

I just figured out my 12e. It was intermittently throwing this code. Especially in the morning. It turns out the black and red wire they zip tied to the gas tube is sparking. When I cut off the zip ties, it started working. I added extra electrical tape to the wire and the gas tube. Let's see if that fixes it for good.

Did that fix the problem now that it's been 4 months? I am getting the e012 code but I can see the flame start through the viewer window but then it stops. Did you have a similar issue? thanks.

Where does the gasket go ?

I change mine and the code still show up and it doesn’t hold the hot water for long. Do you know what else could be causing it to lose hot water?

How old was it when you had to replace the part ?

Thanks for the info! It costed me several hundred last two times to get it fixed. The technician also replaced the flame viewer window (the pill shaped cutout to the left of the Flame Rod; Navien 30028670A Sight Glass Assembly). For whatever reason I seem to need a flame rod every 2 years, but thanks to you, this will not be an expensive repair this time.

3 Days later, all is running well. No more error codes and water is heating up to full 120 degrees.