AEG i20 fault codewhat it means and how to fix it
The machine could not drain. Two beeps on a model without a display, and the filter in the bottom of the tub is the first place to look.
Take care
Does the kitchen sink drain normally?
The right answer depends on what you can see. Pick the one that matches.
Choose the option on the left that matches what your appliance is doing, and the answer for that case appears here.
No, the sink is slow as well
The machine is very likely fine. The blockage is in your plumbing and it is backing the dishwasher up.
Clear the sink trap first and run the machine again before calling anyone out.
Yes, the sink is fine
The restriction is in the machine — filter, hose or pump, in that order.
Work through the filter first. It is the answer far more often than the pump.
What i20 means
i20 is a problem with water drainage, and it also appears as C2, F2 or AL6 depending on the model, or as two beeps on a machine with no display. It is one of the codes AEG expect an owner to have a go at, and the reason is that the parts responsible are all reachable from inside the tub without tools. The filter assembly sits under the bottom basket — a coarse plastic cup with a fine mesh insert — and it catches everything that comes off your plates. Manufacturers expect it to be lifted out and rinsed regularly, and a great many machines have never had it touched. There is a related code worth knowing about, because it catches people who have just cleaned the filter: i23 means the drain pump cover is loose or missing. If you took the filter assembly apart, cleaned it, put it back and immediately got a code, that is the likely explanation, and it is a matter of seating the parts properly rather than a fault at all.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Tub filter clogged | The mesh under the bottom basket, packed with food debris. The first thing to check and the answer more often than anything else. | Common |
| Drain hose kinked or blocked | Often crushed behind the machine, or blocked where it joins the sink waste under the cupboard. | Common |
| Sink waste or trap blocked | Most dishwashers discharge into the kitchen sink waste, so a greasy trap backs the machine up while the appliance itself is perfectly healthy. | Common |
| Waste disposal blanking plug left in | Only after a new disposal unit has been fitted. The spigot it provides for a dishwasher arrives sealed, and if nobody knocked the plug out the machine has nowhere to pump. | Occasional |
| Drain pump failed or jammed | Broken glass and fruit stones are the usual culprits for a jam. The pump itself failing is less common than everything above it. | Occasional |
What to try yourself
Switch off at the wall. Scoop out the standing water with a jug and a sponge before you start — you cannot see anything through it and you will flood the kitchen floor when you lift the filter otherwise.
Give it time to cool if the cycle stopped while hot, and wear gloves. Undissolved dishwasher tablet in that water is strongly alkaline.Take out the bottom basket and twist the filter assembly anticlockwise to release it. Lift out both parts, the coarse cup and the fine mesh, and rinse them under a hot tap with a washing-up brush.
Look into the recess the filter came out of and feel round it for anything hard — glass, a fruit stone, a fragment of crockery — that could be jamming the pump.
Broken glass is the commonest thing found here. Look before you put a hand in, and use a cloth rather than bare fingers.Refit the filter and turn it clockwise until it locks. This matters more than it sounds: a filter left unseated gives i23, the drain pump cover code, which looks like a new fault.
Check the sink drains freely, and check the waste hose under the cupboard for kinks. If the sink is slow, clear that first — the dishwasher is not the problem.
Get a qualified appliance engineer to look at your AEG i20
Vetted local appliance engineers. No obligation.
What it costs to fix
Typical repair cost
£0–£170
Time on site
30 minutes
Usually free. A replacement drain pump is around £100 to £170 fitted. A blocked sink waste is a plumbing job and priced separately.
Typical UK prices including parts and labour, updated August 2026. Your quote may differ.
What other owners found
Nobody has shared what worked for them on this code yet. If you have had it, you would be the first — and it genuinely helps the next person.
Related AEG fault codes
- E24Get it checkedThe machine cannot drain. Bosch publish a full owner procedure for this one, and two warnings about doing it that their UK page leaves out.Related: draining and filter
- F11Get it checkedWater left standing in the cabinet because the machine cannot drain. Miele treat this as an owner job and walk you through the drain pump.Related: draining and filter
- F03Get it checkedDrain failure or timeout — one of only two codes Hotpoint invite you to look at yourself, and usually a blockage.Related: draining and filter
- OEGet it checkedDrainage problem. LG list this twice — once as a running fault and once as an installation fault — and the second is the one people miss.Related: draining and filter
- E3Get it checkedThe dishwasher does not drain. Three flashes on a machine without a display, and Candy tell you exactly how to count them.Related: draining and filter
Common questions about AEG i20
How often should the filter be cleaned?
Monthly is a reasonable habit for most households, more often if you do not rinse plates first. It takes two minutes and it prevents this code, poor cleaning results and most bad smells at the same time.
I cleaned the filter and now I have i23. What did I do?
Almost certainly not seated the filter properly on the way back in. i23 means the drain pump cover is loose or missing. Take it out and refit it, turning until it locks positively rather than just dropping it into place.
Is a bit of water in the bottom normal?
A small amount of clean water sitting in the recess round the filter is normal and deliberate — it stops the seal drying out. Dirty water lying across the tub floor and covering the filter is not.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer support portal
Checked by Appliance technical reviewer (Qualifications to be displayed on appointment) on 5 August 2026.