What this error means
Drainage fault — the dishwasher cannot empty water from the tub within the expected time.
The i20 error on a Zanussi dishwasher means the machine has failed to drain water from the tub within the programmed drain time window. Zanussi dishwashers monitor drainage progress continuously and display i20 when water has not been removed successfully. The most common causes are a blocked or dirty filter assembly at the base of the tub, a foreign object jamming the drain pump impeller, a kinked or incorrectly installed drain hose, or a blocked household sink waste trap preventing water from leaving the machine. A failed drain pump motor will also produce this code.
What you'll need first
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Step-by-step
Symptoms to look for
- Water clearly visible standing in the base of the tub at the end of a programme
- Dishwasher stops mid-cycle with standing water remaining in the tub
- Grinding, rattling, or loud humming from the base of the machine during the drain phase
- i20 displayed near the end of a wash or rinse programme
How to fix it
Unplug the dishwasher from the mains. If the machine stopped mid-cycle there may be hot, soapy water standing in the tub base — have a towel ready to absorb any spillage when you open the door.
Open the door and remove the lower basket. Unscrew the cylindrical coarse filter by turning it anti-clockwise and lift it out. Then lift out the flat fine mesh filter that sits in the recess beneath it. Rinse both filters under warm running water, scrubbing all surfaces with a toothbrush to remove food grease, soap residue, and debris.
With both filter components removed, shine a torch into the sump cavity. Look carefully for glass fragments, small bones, fruit stones, or solid debris blocking the drain pump entrance. Try to rotate the pump impeller very gently using a non-metallic implement such as a wooden cocktail stick. It should turn with slight, even resistance.
Pull the dishwasher forward slightly from under the counter and inspect the drain hose along its full accessible length. Straighten all kinks and bends. The hose end in the standpipe should be no more than 10 to 12 centimetres deep — any deeper creates a continuous syphon that prevents proper drainage. The hose should loop upward to at least 40 centimetres above floor level before descending to the waste connection.
Refit both filter components, locking the cylindrical filter firmly clockwise. Replace the lower basket. Plug in and run a Quick Wash. You should hear the drain pump activate and water should flow from the drain hose within 60 seconds of the cycle starting.
When to call an engineer
- Drain pump impeller will not rotate by hand after filter removal — solid debris is inside the pump body or the impeller is broken
- Drain pump motor hums continuously but produces no water movement — motor winding has failed
- i20 returns immediately after a thorough filter clean and drain hose check
- Burning smell or scorch marks visible beneath the dishwasher near the pump location
Frequently asked questions
How often should I clean the filter on my Zanussi dishwasher to prevent i20?
Can a blocked household drain cause i20 on a Zanussi dishwasher?
What is the correct drain hose installation to prevent i20?
Is it safe to leave water standing in the dishwasher after i20 appears?
🎯 What is likely causing this fault?
⚠️ Estimates based on common faults — not a guaranteed diagnosis. Always verify before ordering parts.
Parts you may need
Enter your model number to filter results to your exact machine
Usually found on a label inside the door frame or on the back panel of the machine.
| Part | Approx. UK Cost | Find it |
|---|---|---|
| Drain pump | £15 - £20 | 🛒 Amazon UK → |
| Drain pump | £15 - £20 | 🏷️ eBay UK → |
ℹ️ Prices are approximate. Always check the part number matches your model before ordering. Not sure of your model number? Find out how to locate it here.