i21
Zanussi Partial Drain Obstruction

Dishwasher shows i21 and water drains very slowly or not at all.

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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

Partially blocked drain hose, Grease build‑up in sink trap spigot, Foreign object in drain pump, Non‑return valve stuck

How to Fix / Troubleshooting

Safety first: Disconnect power and be prepared for water spillage when removing hoses.

  • Clean filters and sump: Remove all filters and clear debris from the sump area.
  • Check drain hose routing: Ensure the hose rises in a high loop under the worktop and then down to the sink trap, without low spots that can collect sludge.
  • Remove and flush hose: Detach the hose from the sink trap and from the dishwasher (if accessible) and flush thoroughly with hot water.
  • Inspect pump and non‑return valve: Access the drain pump from the base, remove the pump cover and check for obstructions. Ensure the non‑return flap moves freely.
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Repair Difficulty

Medium 3/5

Required Part

Drain Hose
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