Computer swap

I would not try it as they need to be reprogrammed by a mechanic otherwise car will not start no matter what an auto parts tell you. They can be rebuilt. Why do you need a PCM?

Entirely different units. The 22003 Optima is actually a Hyundai Sonata with different trim while the Rio was a Kia design in 2003. In reality you could not even take two identically optioned 2003 Kia Rios and swap the computers. The internal security software would simply prevent both cars from starting.

Thank you guys for your responses to my question I put OBD2 tester on it and it will not even read anything.

Check to see if you have power to the OBDII port first, no power and the reader will not connect. There is also the possibility that your reader will not talk to that particular make/model, even if it says it will.
Try a different tool.
What is the problem with the car at the moment?