99 forrester p0733 code incorrect gear ratio 3

Hi I just bougt a 99 Subaru Forrester a few months ago and the check engine light comes on with incorrect gear ratio 3 problem. I was wondering if this means I need to replace the transmission or have it rebuilt. I hear alot of automatic subaru's have had tranny problems and can only assume that this one has been already replaced once or is just starting to act up now.