E06
Defro DHW Temperature Sensor (NTC) Fault

Boiler displays E06, domestic hot water (DHW) temperature unstable or not recognized.

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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.

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Possible Causes

Failed Defro DHW NTC sensor on plate heat exchanger, Loose sensor connection on Defro PCB, Damaged wiring harness to DHW sensor, Scale build-up isolating sensor from water flow

How to Fix / Troubleshooting

Safety: Turn off power and close cold water inlet before removing any DHW components.

  • Locate DHW NTC: On combi-type Defro boilers, the DHW sensor is usually mounted on or near the plate heat exchanger. Identify the sensor and its cable.
  • Check plug and cable: Ensure the connector is fully engaged and free of corrosion. Inspect the cable for damage.
  • Clean around sensor: If accessible, remove the sensor and clean any scale or debris from the sensor tip and the pocket using a soft brush. Do not scratch the sensor surface.
  • Restore and test: Refit the sensor, open the cold inlet, restore power, and run a hot tap. If E06 remains, the sensor likely needs replacement with a Defro DHW NTC sensor.
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Repair Difficulty

Medium 3/5

Required Part

Defro DHW NTC temperature sensor
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