E06
ACV
DHW Temperature Sensor Fault (NTC Open/Short)
Boiler shows E06, domestic hot water temperature is erratic or boiler will not fire for DHW
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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
Faulty DHW NTC sensor, Loose or corroded sensor connector, Damaged sensor cable, Control board fault
How to Fix / Troubleshooting
Safety first: Isolate electrical power before accessing the boiler casing.
- Check DHW sensor location: On ACV combination and tank-in-tank boilers, the DHW NTC is usually inserted into a pocket on the domestic cylinder or plate heat exchanger. Verify the sensor is fully inserted and the retaining clip is secure.
- Inspect wiring: Look for damaged insulation, signs of overheating, or moisture around the DHW sensor cable and connector on the main PCB.
- Reset and test: Reset the boiler and run a hot water tap. If E06 reappears or water temperature swings wildly, the sensor is likely faulty.
- Professional replacement: A technician can measure the NTC resistance at known temperatures and replace the DHW sensor if necessary.
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Repair Difficulty
Medium
3/5
Required Part
DHW NTC Temperature Sensor
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