Siemens Restricted Water Flow / Pump Cavitation

Pump is very loud and coffee flow is slow or intermittent.

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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

Scale buildup in hydraulic circuit, Blocked inlet filter or water filter cartridge, Air in system, Failing ULKA pump

How to Fix / Troubleshooting

Safety first: Allow the machine to cool and unplug before internal inspection.

Step-by-step:

  • 1. Remove water filter: If a Siemens water filter is installed in the tank, remove it and test the machine without it. Replace if flow improves.
  • 2. Bleed air: Run several hot-water draws to purge air from the system. Refill the tank as needed.
  • 3. Descale: Perform a full descaling cycle to clear scale from the pump, thermoblock, and valves.
  • 4. Check tank outlet: Ensure the tank outlet valve opens freely and is not blocked by debris.
  • 5. Professional service: If the pump remains excessively loud and flow is poor, the ULKA pump may be worn and should be replaced by Siemens.
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Repair Difficulty

Medium 3/5

Required Part

ULKA Vibration Pump
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