E432 Moderate Moderate DIY

Navien Tankless Water Heater E432 — Outlet Thermistor Fault

Navien Tankless Water Heater · Error code E432

What E432 Means

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

Symptoms

  • E432 on display
  • Outlet temperature swings
  • Unit shuts down on call for heat

Common Causes

1
Failed thermistor

Element open or shorted.

2
Loose or corroded connector

Bad contact at sensor or PCB.

3
Wiring damage

Pinched or chafed harness.

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.

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.

Common replacement Navien outlet thermistor View on 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 E027 — Gas Type Setting Error E030 E030 — Fan / Combustion Blower Fault

All Navien codes → All tankless water heater codes →

Verified against manufacturer documentation: navieninc.com

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician.