E06
Thermona
DHW Temperature Sensor (NTC) Fault
Boiler shows E06, domestic hot water (DHW) temperature is erratic or boiler will not fire for hot water.
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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 on Thermona plate heat exchanger, Loose or damaged DHW NTC wiring, Scale build-up around DHW sensor pocket, Faulty PCB sensor input
How to Fix / Troubleshooting
Safety: Isolate electrical power and allow hot water components to cool before touching.
- Reset and test: Reset the boiler and run a hot water tap. If E06 appears immediately, the DHW sensor circuit is likely faulty.
- Visual inspection: Locate the DHW NTC on the domestic hot water outlet or plate heat exchanger. Check for damaged cables or loose connectors.
- Clean sensor pocket (engineer level): If accessible, remove the sensor and inspect for scale or corrosion. Clean the pocket and refit with thermal paste if specified by Thermona.
- Resistance measurement (engineer level): Measure the DHW NTC resistance and compare with the Thermona chart. Replace the sensor if readings are incorrect.
- PCB diagnosis: If a new sensor does not resolve E06, the main PCB may be defective and require replacement.
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Repair Difficulty
Medium
3/5
Required Part
DHW NTC Sensor
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