2000 Kia Sephia Error code P0733 3rd gear incorrect ratio

DTC P0733: INCORRECT 3RD GEAR RATIO
Condition
NOTE:If DTCs P0716, P0717, P0748 or P1500 are displayed on scan tool, diagnose prior to DTC P0733.

Shift solenoids "A", "B", and "C", VSS, input/turbine speed sensor and TFT sensor function normally and vehicle speed is 19-32 MPH in 3rd gear. Input/turbine speed sensor and VSS signals indicate that gear ratio is above set value. Possible cause:
Low ATF level.
Low line pressure.
Control valve stuck.
Solenoid valve malfunction.
TCM malfunction.
Forward clutch, 3-4 brake band, one-way clutch No. 1 slippage.
Diagnostic Procedure
Inspect ATF level and condition. Correct as needed. If fluid level and condition is okay, check line pressure. See PERFORMANCE TESTS in appropriate OVERHAUL article. Follow repair recommendations if line pressure is not within specifications. If line pressure is okay, go to next step.
Perform stall speed test. See PERFORMANCE TESTS in appropriate OVERHAUL article. Follow repair recommendations if stall speed is not within specifications. If stall speed is okay, go to next step.
Perform time lag test. See PERFORMANCE TESTS in appropriate OVERHAUL article. Follow repair recommendations if time lag is not within specifications. If time lag is okay, go to next step.
Perform road test. See PERFORMANCE TESTS in appropriate OVERHAUL article. Follow repair recommendations if transaxle shift speeds or shift feel is not as specified. If vehicle shifts at correct speeds and shift feel is acceptable, go to next step.
Clear DTC. Retrieve DTC. If DTC P0733 is still present, replace TCM. If DTC P0733 is no longer present, problem may be caused by intermittent clutch slippage. Further investigation may be required. See SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in appropriate OVERHAUL article.