Navien NPE-A / NPE-S Code E615
Input and memory fault. The board's stored configuration or its inputs are not reading back correctly. Navien's instruction is to contact technical support; there is no owner-side remedy.
Call a proThe verdict
Call a licensed plumber
A board-level fault. Ask what is actually being replaced before agreeing — this can end at reprogramming or at a new board, and the difference is most of the bill.
Typical cost: $200–$1,100
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
- Note the unit's age. On a first-generation NPE a board replacement is a large fraction of a new heater, and that comparison is worth making.
- Book a licensed professional.
Code E615 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: