After replacing the battery on my 96 Pathfinder, it failed the smog test. The smog guy told me there was no "history" in the ECM, said that Imay need to drive it for a few miles in order for the history to build up again. He also told me the smog testing machine is showing a P0325 code in my ECM---Knock Sensor failure. However, the Check Engine light is not on. What's up with this?
How long do I need to drive it before the this "history" builds up again?

Thank you for your help.

I think it depends on the battery you use. Did you use same brand of battery or replace it for a new.

Thank you for your reply. It would appeaer to me that 12 volts are 12 volts, no matter what brand of battery. I do use a battery with at least 625 CCA or more.