Navien NPE-A / NPE-S Code E432
Cold water inlet thermistor 2: open or short circuit. The second cold water inlet sensor is open circuit or shorted. Navien fits more than one inlet sensor and numbers the faults separately, so this is the same class of problem as E421 at a different measuring point.
Part replacementThe verdict
Replace a part
Same story as E421: a cheap sensor and a service call.
Typical cost: $150–$450
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
- Book a service call. Tell them the code number — it identifies which of the two inlet sensors is at fault and saves diagnostic time.
Code E432 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
3 other Navien NPE-A / NPE-S codes point at a thermistor 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: