Sounds like the ink tank is full and the printer is calling for a service engineer - don't panic! Every time you switch on your printer, or change the ink, the printer cleans the heads by flushing ink through them. This leads to a load of waste ink in the bottom of your printer. In order not to get a messy desk Espon have put a counter on the flushing activity and the E90 error is saying this counter has reached the maximum.
To fix this error you need to reset this counter. Try this little utility click here it worked for me