Washing Machine
E21
The E21 error code on an AEG washing machine points to a water drainage problem — specifically, the machine is taking too long to pump water out, or it can’t drain at all. It’s one of the more common fault codes AEG owners encounter, and while it sounds alarming, it’s often caused by something straightforward like a blocked filter or a kinked drain hose. In this guide, we’ll walk you through exactly what’s happening inside your machine, the most likely culprits, and which fixes you can safely tackle yourself before calling in a professional.
What does this error mean?
When your AEG washing machine displays E21, it means the appliance’s control board has detected that the drum isn’t emptying within the expected time — usually around 3 to 5 minutes. The machine monitors water level using a pressure switch (sometimes called a pressostat) and a separate drain pump that’s responsible for pushing water out through the drain hose and into your household waste pipe. If the water level sensor hasn’t dropped to ’empty’ within the allowed window, the machine throws the E21 code and halts the cycle to protect itself from overflow or damage to internal components. In plain terms: water is stuck inside the drum and the machine can’t get rid of it fast enough. This is a drainage fault, not an electrical one, which is good news — it means the most likely fixes are mechanical and accessible.
Est. repair cost
DIY fix (filter clean, hose check): £0–£15 for basic supplies. Drain pump replacement (parts only, DIY): £20–£55. Professional repair including call-out and labour: £80–£160 depending on your region and the engineer’s rates.
🔍 Likely causes
🛠️ Step-by-step fix
Step 1 — Switch off and unplug the machine: Before doing anything else, turn the programme dial to ‘off’, switch off at the wall socket, and unplug the machine. Never work on a washing machine with power connected. If there is standing water in the drum, leave the door closed for now.
Step 2 — Drain any remaining water manually: Locate the small emergency drain hose tucked behind the filter access panel at the bottom front of the machine (consult your AEG manual if you can’t find it). Place a shallow tray or towel underneath, pull out the small black rubber tube, remove the plug, and let the water drain out slowly. This prevents a flood when you open the filter. You may need to empty the tray several times.
Step 3 — Clean the pump filter (coin trap): Once the water is drained, unscrew the large circular filter cap anti-clockwise. Pull it out fully and rinse it under the tap, removing all fluff, debris, coins, or foreign objects. Also reach into the housing with your fingers and clear any blockage from the recess — check for a small impeller you can turn with your finger; it should spin freely. Screw the filter back in firmly to prevent leaks. Tools needed: old towels, a shallow bowl or baking tray.
Step 4 — Check the drain hose for kinks or blockages: Pull the machine slightly away from the wall and visually inspect the entire length of the grey corrugated drain hose from the back of the machine to where it connects to the waste pipe. Straighten any kinks. Disconnect the hose from the wall end and blow through it — if it’s blocked with debris or limescale, flush it through with warm water. Ensure the hose loop is positioned at the correct height (60–100cm) as per your installation manual.
Step 5 — Check your household waste pipe or standpipe: Pour a bucket of water down the standpipe or run the kitchen tap to confirm your household drain is flowing freely. If the sink is draining slowly too, the blockage is in your household plumbing, not the washing machine. Use a sink unblocker or call a plumber.
Step 6 — Run a service wash to clear limescale: If the filter and hose are both clear, limescale build-up on internal components including the pressure switch tube may be contributing to the fault. Run an empty drum clean cycle at 90°C with a washing machine cleaner tablet (such as Dettol Washing Machine Cleaner or Calgon). Do not add laundry detergent. This can dissolve scale deposits affecting the pressure switch and pump.
Step 7 — Reset the machine and run a short test cycle: After completing the above steps, plug the machine back in, select a short spin or rinse-and-spin programme, and watch the machine carefully. Listen for the drain pump — you should hear it working (a steady hum or whirring). If the machine completes the cycle without showing E21, the issue is resolved.
Step 8 — Check if the pump impeller is jammed (advanced DIY): If the filter is clear but the pump sounds like it’s struggling, humming without spinning, or is completely silent during draining, the impeller inside the pump body may be jammed. With the machine unplugged and water drained, you can access the pump by removing the front panel on most AEG models. WARNING: This involves removing machine panels and working near wiring. Only proceed if you are confident doing so. If in doubt, stop here and call a professional.
Step 9 — Do NOT attempt to replace the control board yourself: If all the above checks are clear and the machine still shows E21, the fault may lie with the pressure switch or PCB. These components involve the machine’s electrical system and should only be diagnosed and replaced by a qualified appliance engineer. Attempting to replace a PCB without proper diagnostic tools can result in further damage and will void any existing warranty.
📞 When to call a professional
You should call a qualified appliance engineer if: the filter is clean and the drain hose is clear but the E21 error persists; the pump makes no sound at all during a drain cycle (suggesting motor failure); you can hear the pump running but water isn’t moving (suggesting a seized impeller or internal blockage you can’t access safely); or the error returns within a few cycles after cleaning. When you call, tell the engineer: ‘My AEG washing machine is showing an E21 error code, which is a drainage fault. I’ve already cleaned the pump filter, checked the drain hose for kinks, and confirmed the household waste pipe is clear. The pump [describe what you heard — silent / humming / normal]. The machine is approximately X years old.’ This information will save diagnostic time and may reduce your call-out charge. Look for an engineer registered with the Domestic Appliance Service Association (DASA) or one who specialises in AEG and Electrolux Group appliances (AEG machines are manufactured by the Electrolux Group, so engineers familiar with Electrolux, Zanussi, or Miele appliances will often be comfortable with AEG).
⚖️ Repair or replace?
AEG is a premium appliance brand with generally good parts availability in the UK — most drain pump components and pressure switches are stocked by suppliers such as eSpares, 4ourhouse, and Ransom Spares. If your machine is under 7 years old and has been reliable, repair is almost always the better financial decision. A new drain pump for an AEG washing machine typically costs £20–£55 for the part alone and is a relatively straightforward fix for an engineer, keeping total repair costs reasonable. If your machine is over 10 years old and this is not the first fault, replacement starts to make more sense — particularly as AEG’s newer 9000 series models are significantly more energy-efficient, which adds long-term savings to the argument. A mid-range AEG replacement machine (such as the L6FBG141R or similar 7–8kg model) costs between £450 and £650 from UK retailers. As a general rule of thumb used in the trade: if the repair cost exceeds 50% of the cost of an equivalent new machine, replace it. For a straightforward E21 drain pump fault on a machine under 8 years old, repair wins comfortably.