F0
Junkers
General Sensor Fault / NTC Out of Range
F0 appears intermittently; unit may continue to run but with unstable temperature.
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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
Loose sensor connector, Damaged NTC cable, Sensor partially shorted by moisture, Control board input fault
How to Fix / Troubleshooting
Safety: Disconnect power before opening the control compartment.
- Identify which sensor: Consult the Junkers service manual for your model to see which sensor F0 refers to (flow, return, DHW, or flue).
- Dry and secure: If there are signs of condensation or water near the sensor or connector, dry the area thoroughly and correct any leaks.
- Check cable routing: Ensure sensor cables are not touching hot surfaces or sharp metal edges.
- Reconnect: Unplug and reinsert the sensor connector on the PCB to ensure good contact.
- Monitor: If F0 recurs, the sensor or PCB may need replacement by a service technician.
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Repair Difficulty
Medium
3/5
Required Part
Temperature Sensor (Model-Specific)
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