Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › I have a 2007 Nissan Sentra. I am getting a P0420 code. › I have a 2007 Nissan Sentra. I am getting a P0420 code. August 5, 2019 at 6:17 pm #894161 college manModerator check for any exhaust leaks. if none found then your o2 sensor is reporting that the cat is not cleaning up to spec. A cat would be needed.