Question

2004 Ford Freestar Limited 4.2L with engine code P1633. System ready... ( info... on my scan-tool ) ..... memory ok..!!!..no problem....engine in good condition....why p1633...stay...??? ...for 1 year...

Answer 1

P1633 KAPWR  (Keep Alive Memory Power)

This is more of a circuit power, to help resolve this clean the battery terminal.

 Battery terminal and the battery state of charge are the main cause for code condition such as P1633/ P0603. Check the battery terminal for proper connection and  cleaness

Answer 2

P1633 Ford Code - Keep Alive Power Voltage Too Low
Read more: https://www.autocodes.com/p1633_ford.html