Possible causes

– Low transmission fluid level
– Dirty transmission fluid
– Shift solenoids
– Transmission mechanical problems
– Transmission hydraulic control circuit

Tech notes

There is a Nissan bulletin for the following models:

1995-1996 Nissan Maxima
1995-1997 Nissan Sentra/200SX
1996-1997 Nissan Truck
1995-1997 Nissan Altima
1996-1997 Nissan Pathfinder
1995-1996 Nissan 240SX
1996-1997 Nissan Quest
Nissan Factory Service Bulletin OBDII Code P0731

2002 Nissan Sentra
2002 Nissan Altima
2002 Nissan Sentra and Altima Factory Service Bulletin OBDII Code P0731

When is the code detected?

P0731 is detected when A/T cannot be shifted to the 1st gear position even if electrical circuit is good.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Incorrect transmission shifting

P0731 NISSAN Description

This diagnosis monitors actual gear position by checking the torque converter slip ratio calculated by Transmission Control Module (TCM) as follows:

Torque converter slip ratio = A x C/B

A: Output shaft revolution signal from revolution sensor
B: Engine speed signal from Engine Control Module (ECM)
C: Gear ratio determined as gear position which TCM supposes

If the actual gear position is higher than the position (1st) supposed by TCM, the slip ratio will be more than normal. In case the ratio exceeds the specified value, TCM judges this diagnosis malfunction.

NISSAN Technical Service Bulletins for P0731 code