Buick/Olds: 1996 Buick Park Avenue, Will not start., buick park avenue, battery cables

Question
I just replaced the starter and the starter works fine, so that is NOT the problem. Could it be the ignition switch? Could it be something wrong that makes the ECU not let the car start? After installing the starter I reconnected the battery cables, then went to start the car. The car started, I was quite happy. I turned it off, then tried to start it again. It would not start. Any idea on what the problem is? What did it mean when I turned the car on and the radio showed the code "E 13"?
Thank you for your help.

Answer
that code means "open oxygen sensor circuit.
it could indeed be the ECU  If you can get it to Autozone they'll do a free code check.
FOLLOW UP........
TAKE THE BATTERY CABLE OFF , WAIT 30 SECONDS, THEN PUT IT ON. THIS WILL RESET THE ECU, AND MAY SOLVE YOUR PROBLEM.