Navien NPE-A / NPE-S Code E760
Flushing / service alarm. Not a fault. It is Navien's scheduled service reminder telling you the heater is due a flush. The manual's instruction is to contact the installer to perform routine service — but flushing a tankless heater is a job many owners do themselves with a pump and citric acid.
DIY fixThe verdict
Descale the unit
The cheapest verdict on the site, and the one most worth acting on. A descale kit and acid is roughly $30 to $80 of supplies, or a service call if you would rather not. Ignoring it is how a heat exchanger gets destroyed.
Typical cost: $25–$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
- Flush the heat exchanger — our step-by-step descaling guide covers the whole job.
- Clean the cold water inlet filter while the unit is isolated; it is two minutes and it is already open.
- If your water is hard, shorten the interval rather than waiting for the alarm each time.
Frequently asked questions
Is E760 telling me something is broken?
No. It is a time or usage based reminder that the heat exchanger is due a flush, not a measurement that anything has failed. It is worth acting on precisely because nothing is broken yet — descaling is cheap and a heat exchanger is not.
Code E760 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: