Hiya,
I take it this is the Indesit model?
A03 for an Indesit is stated by them to be :- Failure to drain in alloted time.
Faulty pump or blockage.
If the drain hose goes onto a spigot under the sink, remove this and check there first.
Failing that you will have to unplug the appliance from the wall socket, take the machine out, remove the side panel and remove the pump and drain hose to clear the blockage.
Hope this helps.
Thanks
Home Appliance Technician
Whitegoods engineer working for a multibranded national company in the UK.