E09
Grünbeck Soft Water Hardness Sensor Fault (if equipped)

Display shows E09 and the unit indicates a treated water hardness sensor fault

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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

Soft water sensor fouled by iron or manganese, Cable connection loose, Sensor failure, Incorrect installation position

How to Fix / Troubleshooting

Safety: Disconnect power before working on sensors.

  • Locate sensor: The soft water hardness sensor is typically installed on the outlet side of the Grünbeck softener or in the blending valve assembly.
  • Inspect wiring: Check the connector and cable for moisture ingress or mechanical damage. Dry and reseat the connector.
  • Clean sensor: Remove the sensor and clean the measuring surfaces with a soft cloth and mild descaling solution if iron deposits are present. Rinse thoroughly.
  • Check mounting: Ensure the sensor is installed in the correct flow direction and fully immersed in the water stream.
  • Calibrate: Use the control menu to recalibrate the sensor against a manual hardness test. If calibration fails, replace the sensor.
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Repair Difficulty

Medium 3/5

Required Part

Soft Water Hardness Sensor
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