Hello, This is wierd. 1997 Nissan Alitma 2.4L 4 cyl. In for a pre-test. Runs fine. Failed Nox above 1000 w\EGR connected and functioning. Disconnect EGR and Nox 30. Customer was in a huge hurry so let the car go but we can get it back. All I can figure out is ... Login to read more.