Navien NPE-2 Code E432
Cold water inlet thermistor 2: open or short circuit. The second cold water inlet sensor has an open or shorted circuit. The same class of fault as E421, on the other inlet-side sensor. Navien's instruction is to contact technical support.
Part replacementThe verdict
Replace a part
Same economics as E421: an inexpensive sensor and a service call. Worth mentioning if you have had E421 as well — two inlet sensors failing together points at the harness or the board rather than at the sensors.
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-2 — not averaged across the brand.
Source: Navien NPE-2 User's Information Manual (p. 17), read Aug 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
- Note whether E421 has also appeared — that pattern matters to the technician.
- Contact your installer or Navien technical support.
Frequently asked questions
Both E421 and E432 appeared at once. Is that two failed sensors?
Unlikely. Two sensors reporting open at the same moment usually means the thing they share failed — a connector, a harness, or the board input — not both sensors.
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-2 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: