E06
Main
DHW Temperature Sensor (NTC) Fault
Boiler displays E06, hot water temperature unstable or boiler shuts down during DHW demand
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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 DHW NTC sensor, Loose or damaged sensor wiring, Scaled-up DHW heat exchanger, Faulty PCB sensor input
How to Fix / Troubleshooting
Safety: Turn off power before accessing internal components. Water may be hot; allow to cool.
- Check symptom pattern: Note if E06 appears only on hot water demand and not during central heating. This points to the DHW NTC.
- Inspect DHW sensor wiring: Locate the DHW NTC on the Main plate heat exchanger or DHW outlet pipe and check the harness for damage or loose connectors.
- Run hot tap test: Open a hot tap fully and observe the boiler temperature display. Rapid fluctuations or instant overheat suggest sensor or plate heat exchanger issues.
- Engineer actions:
- Measure DHW NTC resistance and compare with Main’s specification.
- Check the plate heat exchanger for blockage or scale; clean or replace if restricted.
- Verify correct operation of the diverter valve directing flow through the DHW circuit.
- Test the PCB input for the DHW sensor and replace the Main PCB if necessary.
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Repair Difficulty
Medium
3/5
Required Part
DHW NTC Sensor
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