E-91 code means that the "Waste Ink Pad",which soaks up all the normally wasted ink from Head cleaning, etc. is saturated and needs replacing with new one. You cannot do it yourself, as it need resetting the printer sensors, and you'll have to have the printer serviced by an service engineer. Search Google for "Epson printer service" for nearest service shop near where you live. Hope this helps, but it will cost money. Sorry.
Karel, October 2008