DTC P0731: A/T 1ST Gear Function: Description: Notes

This malfunction will not be detected while the A/T CHECK indicator lamp is indicating another self-diagnosis malfunction.
This malfunction is detected when the A/T does not shift into first gear position as instructed by the TCM. This is not caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

Fig 1: Solenoid Valve Operation Table
Courtesy of NISSAN MOTOR CO., U.S.A.