Stolen fron another site.
"My rx520 was working just fine when suddenly i get a message E90 on the screen which means you have to have it serviced (which btw would be more expensive than getting another printer). It turns out this message comes up because epson have installed timers or counters into their printers. so after a certain amount of usage your printer will simply die. Epson's excuse is that it is to prevent ink leaking onto your desk. And seems to be that's all it is - an EXCUSE to RIP YOU OFF, because after all, they could have allowed the scanner to continue working, couldn't they? But no, the whole all-in-one is dead.
Shame, i liked the negative scanning facility."
Try this download to see if it will reset the counter