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. That cover is not the filter itself but the small plastic cover over the pump in the bottom of the sump, which is exposed once the filters are out and can be dislodged while you are working in there. If you cleaned the filters and immediately got i23, that is the likely explanation, and AEG’s fix is to press the cover back into place so it is not loose rather than any repair. AEG also publish the installation figures the drain side has to meet: the drain hose no longer than 400 cm, and its connection into the waste between 40 and 85 cm above the floor.
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.Before the filters go back, check the small plastic cover over the drain pump in the floor of the sump is pressed firmly home. A loose or missing cover gives i23, which looks like a new fault. Then refit the flat filter under its two guides, put the cylinder filter back into it and turn it clockwise until it locks.
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. On a recent installation, check the blanking plug was knocked out of the spigot the hose connects to, and that the connection sits between 40 and 85 cm above the floor with no more than 400 cm of hose, which are AEG’s published limits.
Get a qualified appliance engineer to look at your AEG i20
We do not pass enquiries to a repair firm, so there is no form here. When you book a qualified appliance engineer, tell them the make, the model and the exact code or message on the display, and ask whether they carry parts for this make — that is what turns one visit into a repair rather than a quote.
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 September 2026. Your quote may differ.
Own this appliance and had this code? . Nothing is published until a person has read it.
Related AEG fault codes
- i30Stop — call an engineerThe anti-flood device has triggered — water has collected in the base of the machine. AEG say to close the water tap and call service.Related: same brand
- i10Get it checkedNo water is coming in. One beep on a model without a display, and AEG publish a pressure range you can test against.Related: same brand
- i50Get it checkedA wash pump fault, so water is not being driven round the spray arms. Needs an engineer, but AEG do not treat it as a hazard.Related: same brand
- i40Get it checkedA water level sensor fault — not a dirty filter, whatever the repair sites say. This is the code most commonly misreported online.Related: same brand
- i60Get it checkedThe water inside is too hot, or the sensor that measures it has failed. Note that AEG’s own index describes this one differently from the article behind it.Related: same brand
Own an AEG dishwasher? Save it and its codes come first next time.
Related guides
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 dislodged the drain pump cover while the filters were out. i23 means that cover is loose or missing, and AEG’s own procedure is: switch off and unplug, remove the filter system, sponge out any water, pull the plastic cover off at an angle with a finger, clear any foreign objects from the impeller, then press the cover back so it is not loose and refit the filters. It is a seating problem, not a part.
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.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
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
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.