Navien · Tankless Water Heater Moderate

E432 — Cold Water Inlet 2 Thermistor Fault

The cold water inlet 2 thermistor — the temperature sensor on the second cold-water inlet connection found on units set up with two inlets — is open, shorted, or reading outside its 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 cold water inlet 2 thermistor and reseat its connector.
  3. Measure resistance and compare to the manufacturer's spec chart for the measured water temperature.
  4. Replace the thermistor if the reading is open, shorted, or out of range.
  5. Inspect harness routing for pinches or chafing.

Why it happens

Typical signs: E432 on display · Inlet temperature reading looks wrong or erratic on units with a second cold-water inlet connection · Unit shuts down on a call for heat

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

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 inlet thermistor Common replacement
    Amazon →

More Navien tankless water heater codes

E003 E003 — Ignition Failure E012 E012 — Flame Loss E016 E016 — Overheat / High-Limit Trip E027 Tankless E027 — Sensor Abnormality E030 E030 — Abnormal Exhaust Temperature (Flue Overheat) E046 E046 — Abnormality in Limit Control (Heat-Exchanger High-Limit)

All Navien codes → All tankless water heater codes →

Frequently asked questions

What does the E432 code mean on a Navien tankless water heater?

The cold water inlet 2 thermistor — the temperature sensor on the second cold-water inlet connection found on units set up with two inlets — is open, shorted, or reading outside its expected resistance range.

What causes the E432 code on a Navien tankless water heater?

Failed thermistor: Element open or shorted. Loose or corroded connector: Bad contact at the sensor or PCB header. Wiring damage: Pinched or chafed harness between the sensor and the board.

Is it safe to keep using a Navien tankless water heater with a E432 error?

Yes, with caution. This is rated a moderate-severity fault.

How do I fix E432 on a Navien tankless water heater?

Power off the unit. Locate the cold water inlet 2 thermistor and reseat its connector. Measure resistance and compare to the manufacturer's spec chart for the measured water temperature.

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.