Do a bit of searching before you reach for the woring diagram.
2 minutes on Google (which you DID do, didn't you?) produced thefollowing:
http://www.fixya.com/support/t9736668-err_3_shows_led_screen_delonghi
and
http://howtomendit.com/answers.php?id=47741
The latter seems to suggest there is water leaking into the base and being picked up by a safety device.
Both threads give what appears to be a short term fix.
Read the second thread all through as it suggests apossible cause.
Then learn how to use Google Search
X, March 2015
