I recently purchsed a 2003 Jaguar x-type 2.5. It recently had the transmission replaced by a local repair shop. This took place only roughly about a month ago. Advice?

It would sometimes shift hard between first and second gear. The seller advised me that it needs to be taken to a Jag dealer to get reprogrammed for proper shifting. He also claimed that the car was immediately put up for sale and only driven to his home after repair took place. I called the mechanic whom replaced the tranny and he told me the same thing referring to programing.  The nearest dealer is at least an hour away which would require towing the vehicle to avoid possible damage. I called the local tranny and foreign car garages to see if any could do this programing. Of course, all said no, but I was also told that this model doesn't require programming, it only needs to be reset. I haven't driven the car since buying except short test spins. I have had it parked while I do maintenance to it. I did replace all of the cars fluids including the transmission fluid. I wanted to be sure the proper fluids were in place throughout the Jag. After completing all of this, I took car for a short drive in the neighborhood. It feels like it is now shifting very smoothly. Then after about 10-15 minutes or so red exclamation lights up and car goes into limp. On my personal fault code device. I'm only given one trip code referencing an O2 sensor fault. I did notice my breather hose is collapsing when engine is running. Hose and pvc valve currently on order. Can this also be the cause of car going into limp mode? Or is it pretty much a given I'm going to need to get my car towed to the dealer to program? Is doing a reset to the TMC even an option? Any advice will be greatly appreciated.

Thanks