Navien NPE-A / NPE-S Code E517
DIP switch setting fault. The configuration switches on the board are set to a combination the unit does not accept. This is a settings fault rather than a broken part, which is why it most often appears just after an installation, a board replacement, or a gas conversion — someone set something wrong, or did not finish.
Call a proThe verdict
Call a licensed plumber
Nothing is broken. But the switches configure gas type and unit behaviour, so setting them is not an owner adjustment — usually a short visit rather than a part.
Typical cost: $0–$300
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
- Think about what changed just before this appeared: an installation, a service visit, a board swap, a gas conversion. Tell whoever comes out.
- Do not open the panel to change settings yourself — these switches include the gas type.
- Book a service call. If the unit was worked on recently, call whoever did that work first.
Code E517 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 a switch 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: