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
The same code number can mean something different on another series — make sure you're reading the page for your exact unit:
Don't confuse this with
One other Navien NPE-A / NPE-S code points at flame detection too. They are different components in different places, and ordering a part against the wrong one is the most common way this fault gets expensive: