2005 PT Cruiser engine light showing transmission problems

My 2005 PT Cruiser, 2.4 non turbo model, with 124000 miles recently started tripping the check engine light with the codes p0700 (which I know is just to let you know there was a code) and p0704 indicating the TCC sensor showed an error. Can someone please tell me what would cause this code, what to check, and if this is an easy fix or something that will ultimately result in a transmission overhaul? I have taken this to a repair shop that teaches students how to repair transmissions, but wasn’t very impressed with their “suggestions” as they were varied and changed constantly from possibly just trash in a valve body to needing a torque convertor to even a total overhaul. Any advice/suggestions is greatly appreciated as transmissions are not my forte.