1998 Saturn sc2 transmission problem

1998 Saturn sc2. got stuck in snow tried rocking car to get it out didn’t work had to be pushed out. after that check engine light on and when i get to about 40 mph wont go in to overdrive. ran diagnostics came back with code PO734 gear 4 incorrect ratio. what does that mean? do i need a new tranny or are there other things i can do first to try and fix without having to replace tranny?