First thing I would do is go to Nissan's site or contact a dealer or Nissan's customer hotline (1-800-NISSAN-1) and see if there are any open campaigns or recalls on your vehicle; you will need your VIN #. There was a voluntary recall issued by Nissan 2012-2014 Versas to reprogram the CVT's transmission control module due to belt slipping caused by low hydraulic pressure. For more details, you can view the bulletin here:
https://static.nhtsa.gov/odi/tsbs/20...58388-9756.pdf