DTC P0730: Incorrect Gear Ratio: Notes

WARNING: This page is about a different car, the 2020 Subaru Impreza. However, it is still accessible from the selected car via links, so may be relevant.

1. -

DTC detecting condition:

Immediately at fault recognition

Trouble symptom:

Acceleration is poor during standing start.
Shift control malfunction
Engine speed increases abruptly.

CAUTION: After servicing or replacing faulty parts, perform the last step of the basic diagnostic procedure. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>BASIC DIAGNOSTIC PROCEDURE .

Courtesy of SUBARU OF AMERICA, INC.

CHECK TRANSMISSION FLUID .
Check the amount of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>CVTF>ADJUSTMENT .

Is the check result OK?

Yes : Go to 2.

No : Adjust the amount of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>CVTF>ADJUSTMENT .
CHECK TRANSMISSION FLUID .
Check the condition of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>CVTF>CONDITION CHECK .

Is the check result OK?

Yes : Go to 3.

No : Check according to the "Corrective action" of ATF (CVTF) "CONDITION CHECK". Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>CVTF>CONDITION CHECK .
CHECK INPUT SIGNAL FOR TCM .
1. Lift up the vehicle.
2. Start the engine.
3. Warm up until the ATF temperature reaches to 40 - 70°C (104 - 158°F).
4. Depress the brake pedal, and shift the select lever to "D" range.
5. Shift the select lever to "P" range.
6. Stabilize the engine speed at idle.
7. Using the Subaru Select Monitor, read data of [Actual Secondary Pressure] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>DATA MONITOR .
Is [Actual Secondary Pressure] 0.5 - 1.5 [MPa]?

Yes : Go to 4.

No : Perform the diagnosis according to DTC P0841. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEDL)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC P0841 TRANSMISSION FLUID PRESSURE SENSOR/SWITCH "A" CIRCUIT RANGE/PERFORMANCE .
CHECK INPUT SIGNAL FOR TCM .
1. Set the select lever to "D" range.
2. Release the brake pedal to stabilize the engine speed and front wheel speed.
3. Using the Subaru Select Monitor, read data of [Actual Gear Ratio] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>DATA MONITOR .
Is [Actual Gear Ratio] 1.5 - 2.6?

Yes : Go to 5.

No : Go to 6.
CHECK INPUT SIGNAL FOR TCM .
1. Set the select lever to "D" range.
2. Slowly increase the speed to 40 km/h (25 MPH) and keep the constant speed.
3. Using the Subaru Select Monitor, read data of [Actual Gear Ratio] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>DATA MONITOR .
Is [Actual Gear Ratio] 0.5 - 0.9?

Yes : Go to 6.

No : Replace the transmission assembly. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>AUTOMATIC TRANSMISSION ASSEMBLY .
DRIVING CHECK BY INSPECTION MODE .
1. Using the Subaru Select Monitor, perform the clear memory of [Transmission]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
2. Execute the inspection mode. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>INSPECTION MODE .
Does the AT OIL TEMP light blink and is DTC P0730 displayed?

Yes : Replace the transmission assembly. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>AUTOMATIC TRANSMISSION ASSEMBLY .

No : Current condition is normal. It is possible that temporary poor contact occurs.