DTC P0868 Secondary Pressure Down: Description

WARNING: This page is about a different car, the 2007 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.

The pressure control solenoid valve B (secondary pressure solenoid valve) is included in the control valve assembly.
The pressure control solenoid valve B (secondary pressure solenoid valve) regulates the secondary pressure to suit the driving condition in response to a signal sent from the TCM.