Navien NPE-A / NPE-S Code E012
Flame loss. The burner lit and then the flame was lost or stopped being detected. Navien gives owners two things to check: the intake air filter, and that the electrical cord is properly grounded. Both are worth doing because both are free, and a starved air intake is a genuinely common cause on this generation.
Call a proThe verdict
Call a licensed plumber
Sometimes free — a clogged intake air filter is one of Navien's two named causes and cleaning it is routine maintenance. If a clean filter and a grounded cord do not fix it, this is gas and flame sensing work.
Typical cost: $0–$900
US estimate for parts and labor. Prices vary by region and by who does the work — see how we estimate costs.
What the manual says
The meaning above is transcribed from the manufacturer's diagnostic documentation for the NPE-A / NPE-S — not averaged across the brand.
Source: Navien NPE Operation Manual (NPE-A / NPE-S) (p. 16), read Aug 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
Before anything else: if you smell gas, stop here, leave, and call your gas utility.
- If you smell gas, leave the building and call your gas utility from outside.
- Clean the intake air filter. Navien lists it first, and it is a job you can do.
- Confirm the unit is plugged into a properly grounded outlet.
- If the code returns after both, book a licensed professional.
Code E012 on other Navien series
Other Navien series report code E012 under the same fault name, but each manual is transcribed separately and they do not read alike:
Don't confuse this with
One other Navien NPE-A / NPE-S code points at flame detection too. They are the same symptom reported from a different place in the unit, so which one the display shows is what tells you where to look: