Navien water heater shows E432; unit may lock out.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Open or shorted return thermistor, Loose sensor connection, Damaged sensor cable, Defective return temperature sensor

Safety: Turn OFF power and allow heating pipes to cool before handling.

Steps:

1. Locate return sensor: Find the return water temperature sensor on the heating return line.
2. Inspect connection: Ensure the sensor is firmly attached and the wiring connector is secure.
3. Check cable: Look for damage or pinched sections along the cable route.

If E432 persists, replace the return thermistor or contact a technician to do so.

Medium 3/5

Return Temperature Sensor

Check Price on Amazon

We may earn a commission from links on this page.