E40, E41, or four beeps or flashes on a compatible AEG indicates the door or lid is not closed properly or is not being recognized. Check the closure with the machine stopped.
Front door or top lid
The manufacturer documentation covers both designs. Check the PNC manual to identify which latch must fully engage; a top lid may have different components than a front door.
If it opens normally, remove any trapped laundry and reduce the load if it is preventing closure. Check the latch and its fit without inserting objects. Close it normally and use the panel start control. Do not slam the lid or hold the latch down during the wash.
Mechanical child lock, when present
Some models include a mechanical device that changes how the closure works. Check it only if the manual identifies it and explains its position; do not confuse that function with the electronic button lock.
If the appliance still does not recognize a free and properly closed door, note whether the warning appears before water is drawn and request service. If the problem is that it will not open anymore, see door and safety lock before trying to free laundry.
A physically closed door may still not be recognized; the code alone does not identify the faulty component.