UK Appliance Repair Questions? Ask a Technician for Answers ASAP
F05 would indicate a blockage in the pump.
Drain the water down and take out the filter, ensure there is nothing there to block the impellor. If all clean in there unplug the appliance from the wall socket and pull the machine out.
Tip it back about 45 degrees (assistance would be good) and check the hoses to and from the pump for debris. (you'll need to disconnect the hoses from the pump to do this properly).
If everything there is clean and clear then you need to check the pressure system on the appliance.
Take the lid off, locate the pressure switch and take the thin tubing off, blow down as hard as you can into the tubing. Refit it, and try the machine again.
Basically, your machine is taking too long to drain or it's taking too long for the pressure switch to reset.
Hope this helps.
Let me know if you need further help or anything clarifying.