A7
Junkers
DHW temperature sensor (NTC) fault
Boiler shows A7; domestic hot water temperature is unstable or incorrect
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 DHW NTC sensor, Loose or corroded NTC connector, Broken cable between NTC and control board, Scale build-up around sensor pocket
How to Fix / Troubleshooting
Safety: Isolate electrical power before removing covers. Water may be hot; use caution.
- Reset boiler: Turn the boiler off and on, then run a hot water tap to see if the error reappears.
- Check DHW flow: Ensure adequate water flow at the tap; very low flow can cause temperature fluctuations.
- Access DHW NTC (technician recommended):
- Remove the front panel and locate the DHW NTC sensor on the plate heat exchanger or DHW outlet pipe.
- Inspect the connector for moisture, corrosion, or loose fit; clean and reseat.
- Measure resistance of the NTC at known temperature and compare with Junkers resistance table; replace if out of range.
- Check for heavy limescale in the sensor pocket or plate heat exchanger; descale if necessary.
Advertisements
Repair Difficulty
Medium
3/5
Required Part
DHW NTC Temperature Sensor
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements