My Asko W6441 front load washer F3 message

Hello. You said that you checked the drain line for obstructions, but did you check the pump? I would remove the hoses from the pump and using a flashlight, look into the suction port on the pump. Check the pump for any obstructions (like the occasional stray sock) and check the pump impellers. Look for broken/missing blades and ensure that the impeller spins freely. If there are missing/broken blades or if you cannot get the impeller to spin freely, the pump is defective. You may have already done this, and if so I apologize. Anyway, hope this helped and best wishes.