Possible causes

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

Tech notes

Start by inspecting the transmission fluid level and condition, and change fluid if necessary.

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 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.

P0731 Information for specific makes

P0731 ACURA
P0731 AUDI
P0731 BMW
P0731 CHRYSLER
P0731 DODGE
P0731 FORD
P0731 HONDA
P0731 HYUNDAI
P0731 INFINITI
P0731 JEEP
P0731 KIA
P0731 LAND-ROVER
P0731 LEXUS
P0731 MAZDA
P0731 MITSUBISHI
P0731 NISSAN
P0731 SATURN
P0731 SUBARU
P0731 SUZUKI
P0731 TOYOTA
P0731 VOLKSWAGEN