E3
Junkers Return NTC sensor open or short circuit

Boiler shows E3; return temperature sensor fault

Advertisements

Safety Warning

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.

Advertisements

Possible Causes

Defective return NTC, Loose or corroded connector, Damaged wiring harness, Sensor not properly attached to return pipe

How to Fix / Troubleshooting

Safety: Turn off power before opening the boiler casing.

  • Locate return NTC: Find the sensor on the return pipe entering the heat exchanger.
  • Check attachment: Ensure the sensor is firmly clipped to the pipe and has good thermal contact.
  • Inspect connector: Reseat the connector and check for moisture or corrosion.
  • Technician checks:
    • Measure resistance and compare with Junkers NTC table.
    • Replace the return NTC if defective.
Advertisements

Repair Difficulty

Medium 3/5

Required Part

Return NTC Temperature Sensor
Check Price on Amazon

We may earn a commission from links on this page.

Advertisements