Accidentally cracked the OBD2 port housing, how can I replace it?

They sell it that way because the wires have terminals on the end that have tabs which clip into that housing, so they don't push out the back when a scan tool is inserted. How bad is it cracked? Could you take a picture of it and post it? Generally, as long as it's functional it isn't a big deal. As for getting a replacement, the easiest way would likely be to visit a salvage yard and cut one out of another Kia. While the format of the connector and the wire positions are set in standards the size of the wire terminals and where the clips are can be different. So, you could get a shell online and have it not fit your wiring. You will also need to look at how to de-pin each terminal to move it to the replacement shell. This isn't hard to do usually. That is why a salvage part would be a good thing as well; you can practice on it first.