DTC B2126: Detent SW: Description

WARNING: This page is about a different car, the 2013 Nissan Armada. However, it is still accessible from the selected car via links, so may be relevant.

Park position switch is installed on A/T shift selector. It is turned OFF when the A/T selector lever is in P position.
The driver seat control unit judges that the A/T selector lever is in P position if continuity does not exist in this circuit.