DTC P0845 Transmission Fluid Pressure Sensor B Circuit (PRI Pressure Sensor): Description

WARNING: This page is about a different car, the 2008 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.

The transmission fluid pressure sensor (primary pressure sensor) is included in the control valve assembly.
The transmission fluid pressure sensor (primary pressure sensor) detects primary pressure of CVT and sends TCM the signal.