1999 Other Saturn Models ECM showing not ready

I recently had a code cleared, then went to get my car inspected NY state, they put the machine on and it came up that three of the four polution sensors came up not ready so it won't pass the inspection I drove the car another 800 miles to see if the sensors come in and they still do not, the gentleman said it might be a computer (ecm) problem that is why I am writing you to see if you can help on what to do next I do not want to go out and start replacing things without knowing what is the real problem so if you can help me in any way that would be great.

Thank you