Possible causes – Transmission Fluid Pressure Sensor A harness is open or shorted – Transmission Fluid Pressure Sensor A poor electrical connection – Faulty Transmission Fluid Pressure Sensor A – Transmission Valve Body Tech description There is a service bulletin for the P0840 code for the following Nissan Models: 2007-2008 Nissan Altima 2007-2008 Nissan Rogue…