ECU repalcement on 2001 Saturn SC2

I replaced the ECU and now the car will not start. All the numbers match the old ECU. I put the old one back in and it will start. What may cause thisissue with the new ECU?

Asked by for the 2001 Saturn SC2
1 answer
It is possible that it needs programmed upon installation. You may want to consult a Saturn specialist.

Here is a link to some shops near you...