PCM reprogrammed?

98 Sunfire. I bought a used PCM from a junkyard, car was showing codes after install, and it didnt fix the anti-theft issue . . . junkyard guy said the PCM must be reprogrammed, my inside mechanic guy said it doest need to be, just install and re-learn the anti theft (flashing light) and would be good to go.

So does it need re-programmed? Dealership?

Yes, it has to be reprogrammed.....