Navien tankless water heater code E517
DIP switch setting fault. Code E517 means the same thing on all 2 Navien series documented here — but the fix, and what it costs, is still worth reading for your exact unit.
What code E517 means on each Navien series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| NPE-2 | DIP switch setting fault | Call a pro | $0–$300 |
| NPE-A / NPE-S | DIP switch setting fault | Call a pro | $0–$300 |
Each row opens the full page for that generation. We hold manuals for NPE-2 and NPE-A / NPE-S, and each one gets its own reading of code E517 — what Navien documents, what you can safely check yourself, and what the repair should cost.
What each manual actually says
The table above compares 2 series in four columns, which is enough to route you and not enough to explain anything. This is the Navien wording behind each row, one entry per manual, so you can see where the 2 readings of code E517 agree and where they part company.
NPE-2 — DIP switch setting fault
The DIP switches inside the unit — the physical switches that tell the board what model it is and how it was installed — are in a combination the heater does not accept. Navien's instruction is to contact technical support.
NPE-A / NPE-S — 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.
Does it matter which Navien you have?
NPE-2 and NPE-A / NPE-S all route code E517 the same way: a professional, at $0–$300. That makes it one of the Navien numbers you can act on before working out which unit you own.
Which Navien do you have?
On the 2 series that report code E517, the model number on the rating label starts NPE — match yours against the 13 listed below. You can also use the full model-number decoder.
Where this comes from
Source: Navien NPE-2 User's Information Manual (p. 17), read Aug 2026 — the manufacturer's own documentation for this Navien range.
Source: Navien NPE Operation Manual (NPE-A / NPE-S) (p. 16), read Aug 2026 — the manufacturer's own documentation for this Navien range.
Parts, guides and symptoms behind code E517
Code E517 on these 2 Navien series points at 1 part and 1 symptom, each named by the manufacturer's own procedure for this code.