DTC P0730: Incorrect Gear Ratio: Notes

WARNING: This page is about a different car, the 2022 Subaru WRX. 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)>BASIC DIAGNOSTIC PROCEDURE

CHECK DTC .
Read the DTC of [Transmission] using the Subaru Select Monitor. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)

Besides DTC P0730, is any of the DTC P2746, P2747, P2750, P2751, P1706, P170B, P0720 or P0721 displayed?

Yes : Perform the diagnosis according to DTCs other than P0730. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST

No : Go to 2.
CHECK TRANSMISSION FLUID .
Check the amount of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>INSPECTION

Is the check result OK?

Yes : Go to 3.

No : Adjust the amount of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>INSPECTION Go to 3.
CHECK TRANSMISSION FLUID .
Check the condition of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>REPLACEMENT

Is the check result OK?

Yes : Return ATF. Go to 4.

No : Follow the "Corrective action" of ATF (CVTF) "CONDITION CHECK". Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>REPLACEMENT Go to 4.
CHECK INPUT SIGNAL FOR TCM .
1. Start the engine.
2. Warm up until the ATF temperature reaches to 40 - 70°C (104 - 158°F).
3. Depress the brake pedal, and shift the select lever to "D" range.
4. Shift the select lever to "P" range.
5. Stabilize the engine speed at idle.
6. Using the Subaru Select Monitor, read data of [Actual line press.] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS)>DATA MONITOR
Is [Actual line press.] 0.5 - 1.5 MPa?

Yes : Go to 5.

No : Perform the diagnosis according to DTC P0867. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC P0867 TRANSMISSION FLUID PRESSURE
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)>DATA MONITOR
Is [Actual Gear Ratio] 2.0 - 2.7?

Yes : Go to 6.

No : Go to 7.
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)>DATA MONITOR
Is [Actual Gear Ratio] 0.5 - 1.3?

Yes : Go to 7.

No : Replace the transmission assembly. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TRANSMISSION ASSEMBLY
DRIVING CHECK BY INSPECTION MODE .
1. Using the Subaru Select Monitor, perform the clear memory of [Transmission]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY
2. Execute the inspection mode. Ref. to TRANSMISSION (DIAGNOSTICS)>INSPECTION MODE
Does the AT OIL TEMP light blink and is DTC P0730 displayed?

Yes : Replace the transmission assembly. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TRANSMISSION ASSEMBLY

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