Dishwasher
I20
The I20 error code on an Indesit dishwasher signals a drainage problem — the appliance isn’t able to pump water out as it should, and has stopped the cycle to protect itself from overflowing. It sounds alarming, but in many cases this is something you can sort yourself in under an hour with no specialist tools. In this guide, we’ll walk you through exactly what’s causing it, what you can safely fix at home, and when it’s time to call in a professional.
What does this error mean?
The I20 error code is Indesit’s way of telling you that the dishwasher has detected a drainage fault. Specifically, the appliance’s control board has monitored the drain cycle and found that water is not leaving the machine at the expected rate — or at all. This is typically detected by a pressure switch or water level sensor that notices standing water remains in the sump (the basin at the bottom of the dishwasher) after the drain pump should have emptied it. The machine locks itself out of further operation to prevent flooding your kitchen floor. Think of it as the dishwasher saying: ‘I tried to drain, but something isn’t letting me.’ The good news is that the fault is usually mechanical rather than electronic — blocked filters, kinked hoses, and clogged pumps are far more common culprits than a failed circuit board.
Est. repair cost
DIY filter clean: free. Replacement drain pump (DIY part): £15–£35. Professional repair (call-out, parts & labour): £80–£150.
🔍 Likely causes
🛠️ Step-by-step fix
Step 1 — Reset the dishwasher first: Before doing anything else, switch the dishwasher off at the wall socket, wait 60 seconds, then switch it back on and attempt a new cycle. Occasionally a one-off sensor glitch triggers the I20, and a hard reset clears it. If the error returns immediately, move on to the steps below.
Step 2 — Remove any standing water from the tub: Open the door carefully and check whether there is standing water sitting in the bottom of the machine. If there is, use a jug and some old towels to scoop and soak up as much as possible before proceeding. This makes the next steps much easier and less messy.
Step 3 — Clean the drain filter assembly (tools needed: just your hands): Locate the cylindrical filter in the centre of the dishwasher floor — on most Indesit models it twists a quarter-turn anticlockwise to release. Lift it out along with the flat mesh filter beneath it. Rinse both thoroughly under the tap, scrubbing away grease and debris with an old washing-up brush. This single step resolves the I20 error in a large proportion of cases.
Step 4 — Inspect and clean the sump area: With the filters removed, shine a torch into the sump cavity and feel around carefully (wear rubber gloves) for any foreign objects — broken glass, a small bone, a fruit stone — that may be blocking the entry to the drain pump. Remove anything you find.
Step 5 — Check the drain hose for kinks (tools needed: torch): Carefully pull the dishwasher forward a few centimetres to inspect the drain hose at the back. Look for any sharp bends, kinks, or sections where the hose has been crushed against a cabinet wall. Straighten any kinks you find and ensure the hose has a gentle curve rather than a tight bend.
Step 6 — Check where the drain hose connects to your sink waste or standpipe: Disconnect the drain hose end from your under-sink waste connector or standpipe. Check the connection for a build-up of greasy sludge or debris. Pour a little hot (not boiling) water through the connection point to clear any partial blockage, then reattach the hose securely.
Step 7 — Check the drain hose high-loop: Indesit recommend the drain hose is looped up to at least 40cm above floor level before it drops to the waste connection, to prevent back-siphoning. If your hose runs directly downward without this loop, secure it in a high position using a cable tie or hose clip attached inside the cabinet. This alone can resolve persistent I20 errors.
Step 8 — Manually test the drain pump (with caution): Reassemble the filters, run a short rinse cycle, and listen carefully at the base of the machine during the drain phase. You should hear a distinct hum or whirr from the drain pump. If you hear nothing, a grinding noise, or intermittent buzzing, the drain pump impeller is likely jammed or the pump is failing — do not attempt to open the appliance base to access the pump yourself, as this involves electrical components. Call a professional at this point.
Step 9 — Run a hot maintenance wash: If you’ve cleaned the filter and hose and the machine now drains, run a full 65°C or 70°C cycle with a dishwasher cleaner tablet (such as Finish Dishwasher Cleaner) and no dishes loaded. This helps dissolve any remaining grease in the pump and hose. In hard water areas of the UK, doing this monthly helps prevent the I20 error recurring.
Step 10 — If the error persists after all of the above: The fault is most likely a failed drain pump, a faulty pressure switch, or an internal wiring issue. At this point, stop DIY attempts and contact a qualified appliance engineer — further investigation requires partial disassembly of the appliance and access to live electrical components.
📞 When to call a professional
You should stop DIY attempts and call a qualified appliance repair engineer if: the I20 error returns immediately after you’ve thoroughly cleaned the filter and hose; you can hear the drain pump attempting to run but failing (grinding, buzzing, or nothing at all); or you’ve completed all the steps above and the machine still won’t drain. When you call, tell the engineer the exact error code (I20), the model number (found on the inner door frame), and describe what you’ve already tried — this saves time and may reduce your call-out charge. Ask specifically whether they carry Indesit drain pumps, as parts availability varies. You do not need a Gas Safe engineer for a dishwasher; any reputable domestic appliance repair engineer is appropriate. Check reviews on Checkatrade or Rated People for a local specialist.
⚖️ Repair or replace?
For a drain pump replacement — the most common professional repair for an I20 fault — you’re typically looking at £80–£150 all-in for a UK call-out, parts, and labour. Indesit is a widely sold brand in the UK (part of the Whirlpool group), so spare parts including drain pumps are generally available and not expensive (£15–£35 for the part alone if you’re confident doing it yourself). As a rule of thumb: if your Indesit dishwasher is under 5 years old, repair is almost always the right call. Between 5 and 8 years old, repair makes sense if the quote is under £120 and no other faults are present. Over 8–10 years old, or if the repair quote exceeds £150, it’s worth seriously considering a replacement — a new mid-range Indesit or equivalent dishwasher starts at around £250–£350. Bear in mind that older Indesit machines in hard water areas (most of England) often develop multiple issues around this age, so a drain pump fix today doesn’t guarantee trouble-free running tomorrow.