'98 caravan failed NJ inspection O2 sensor "Not Ready"



Hi, My '98 Caravan failed NJ inspection last month due to the oxygen sensor, catalytic converter & EGR were all “Not Ready”. The inspector told me to drive it around alot & come back. I drove for 1400 additional miles and the 3 items still are “Not Ready.” The check engine light has not been on at all and the car has been running great. I did have a new engine & transmission installed over a year ago and a new battery installed about 5 months ago. Any idea what could be causing this and how can I resolve this issue?