I have a fairly new Pixma 5722 and had the same error come up - b203 . I had printed many invitations that used a lot of ink, strange thing is, it didn't come up during or just after printing them, it was when I went to use it again much later. I read all the suggestions above but couldn't do some as the error wouldn't let me access the menu. A 2nd error showed up a few times, can't remember the #, 405 maybe - said I had the wrong print head and to change it! I did try to access the menu thru the computer to realign the head, but you can't. I then looked on Youtube and found a few videos that suggested a hard reset - that did the trick! I did an auto alignment after it came on just in case and is now working fine. Hope this helps others.