Never heard of a "region code" on a HP printer. But their ink does have an expiration date and while it usually will still be fine, in some cases, it just won't work. Had one cartridge, that while it was still in the factory wrap, was past the date and would not print. I did not try to clean the printhead, but it may have helped. Also, most of the newer HP printers, starting about 3 years ago, started using ink tanks, with the printhead inside the printer and not on the cartridge. Makes it easier to just refill the one or two colors that are low and much less costly. But you do need to replace the printheads every 30K - 40K pages or so.