Navien · Tankless Water Heater Moderate

E432 — Outlet Thermistor Fault

The hot-water outlet temperature sensor is open, shorted, or out of expected resistance range.

Keep using it?
Yes, with caution
DIY difficulty
Moderate
Verified against
navieninc.com ↗

How to fix it

  1. Power off the unit.
  2. Locate the outlet thermistor; reseat the connector.
  3. Measure resistance and compare to the spec chart for the measured pipe temperature.
  4. Replace the thermistor if reading is open, shorted, or out of range.
  5. Inspect harness routing for damage.

Why it happens

Typical signs: E432 on display · Outlet temperature swings · Unit shuts down on call for heat

  • Failed thermistor Element open or shorted.
  • Loose or corroded connector Bad contact at sensor or PCB.
  • Wiring damage Pinched or chafed harness.

Parts you may need

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

  • Navien outlet thermistor Common replacement
    Amazon →

More Navien tankless water heater codes

E003 E003 — Ignition Failure E003C E003C — Cascade Ignition Failure E012 E012 — False Flame / Flame Loss E016 E016 — Overheat / High-Limit Trip E027 Tankless E027 — Sensor Abnormality E030 E030 — Abnormal Exhaust Temperature (Flue Overheat)

All Navien codes → All tankless water heater codes →

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: navieninc.com.