Navien NPE-A / NPE-S Code E782
Main panel communication fault. The unit has lost communication with its main panel. Navien's instruction is to contact technical support.
Call a proThe verdict
Call a licensed plumber
A communication fault between the control board and the panel — cabling, connector, or one of the two boards. Diagnosis is inside the cabinet.
Typical cost: $150–$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
- Note whether the display is blank, frozen, or showing the code — that distinction narrows it before anyone arrives.
- Book a licensed professional.
Code E782 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: