Before you start, it helps to know which fault you are actually dealing with. The i10 code fires immediately at the start of a cycle when the dishwasher detects no water entering whatsoever — the inlet valve may not be opening at all, or the water supply is completely off. The i11 code is different: water does begin to enter, but the fill is so slow that the machine times out before reaching the correct level. This distinction matters because i11 almost always points to a partial restriction somewhere in the water supply path rather than a complete failure. If you are seeing i11, work through the steps below in order.

Press the power button to turn the dishwasher off. Locate the isolator valve on the inlet hose under your sink or behind the machine — it is a small inline tap on the hose itself. Turn it clockwise until it stops to shut off the water. If you cannot find an isolator valve, turn off the stopcock under your sink instead. This makes it safe to disconnect hoses and inspect parts without water spraying out.

With the water supply off, unscrew the inlet hose from the back of the dishwasher by turning the connector anticlockwise. Have a small towel ready as some residual water will drip out. Look into the end of the hose connector — you will see a small mesh filter screen inside. This screen catches debris from the water supply and can become blocked over time, especially in hard water areas. Use a flat-head screwdriver or a pair of tweezers to carefully pull the mesh screen out. Rinse it under a running cold tap and use an old toothbrush to remove any lime scale or sediment. If the screen is damaged or corroded, replace it (a new screen costs around £2–5 and is available from any appliance parts supplier). Reinsert the clean screen firmly before reattaching the hose.

Reconnect the inlet hose finger-tight, then pull the dishwasher away from the unit carefully — most slide straight out. Run your hand along the full length of the inlet hose from the machine to the wall connection. Feel for any sharp bends, kinks, or areas where the hose has been pinched against a cabinet wall or the machine itself. Straighten any kinks gently. If the hose has a permanent crease or crack, it will need replacing — a standard dishwasher inlet hose costs £8–15 and is a straightforward swap. Also check the hose is not longer than necessary; excess hose coiled behind the machine is a common cause of kinking.

Restore the water supply and place a jug or bucket under your kitchen tap. Run the cold tap fully open and time how long it takes to fill one litre (most jugs are marked). A healthy supply should fill one litre in under 6 seconds. If it takes longer, your mains pressure is likely too low for the dishwasher to fill within its timeout window. Low pressure can be caused by a partially closed stopcock, high demand on the local supply, or a problem with your incoming mains. Check your main stopcock (usually under the sink or where the supply enters the house) is fully open. If pressure remains low with it fully open, contact your water supplier.

If the hose, filter and pressure all check out, the water inlet valve itself may be partially faulty. This is a small electrically operated solenoid valve mounted at the back of the dishwasher where the inlet hose connects to the machine. With the dishwasher unplugged and the water supply off, remove the back panel (usually held by 4–6 screws around the edge). Locate the inlet valve — it is the component where the hose attaches, with one or two wire connectors plugged into it. Inspect the valve for any visible cracks, corrosion, or lime scale build-up around the inlet port. Disconnect the wire connectors and use a multimeter set to the resistance (Ω) setting — place a probe on each terminal of the valve. A healthy inlet valve reads between 200–500 ohms. A reading of zero (short circuit) or infinite resistance (open circuit) confirms the valve has failed and needs replacing.

A replacement AEG dishwasher inlet valve costs £20–£45 depending on your specific model. Before ordering, locate your model number — it is printed on a label inside the door on the left-hand side when you open it. To fit the new valve: with the machine unplugged and water off, disconnect the hose and wire connectors from the old valve, remove the 2–3 screws holding it in place, and fit the new valve in reverse order. Make sure the hose connector is hand-tight plus a quarter turn — over-tightening can crack the plastic fitting. Restore the water supply slowly and check for leaks before pushing the machine back into position and running a test cycle.

Once you have completed whichever steps applied to your situation, plug the dishwasher back in, restore the water supply fully, and run a short cycle such as a rinse-only or quick wash programme. Stay nearby for the first 5 minutes and watch for any leaks around the hose connections. If the i11 code does not return and the machine fills normally, the fault is resolved. If the error returns immediately, the inlet valve is most likely the cause and should be replaced. If the machine fills but very slowly even after all the above steps, call a qualified engineer as the fault may be with the pressure sensor or control board.