P0734 on Kia
Gear 4 Incorrect Ratio
P0734 on Kia vehicles indicates gear 4 incorrect ratio. Au7o has documented this code across 2 Kia models — most commonly on Sorento, Sportage. This code means the Transmission/Powertrain Control Module detected an incorrect gear ratio in 4th gear. The module continuously compares input shaft speed to output shaft speed; if the ratio in 4th gear doesn't match the expected value, it sets P0734. This usually indicates the transmission is slipping or not fully engaging 4th gear due to a hydraulic, friction, or solenoid problem. Symptoms include slipping, flaring RPM, harsh or missed shifts, and possibly limp mode. Typical repair costs on Kia range from $400 to $2,500, depending on the specific model and root cause.
Common Causes of P0734
- •Low or degraded/burnt transmission fluid
- •Slipping clutch packs or worn friction elements in 4th gear
- •Stuck or faulty shift solenoid
- •Valve body / internal hydraulic leak or restriction
- •Worn or failing torque converter
- •Faulty input or output speed sensor
- •Internal mechanical wear (bands, planetary gears)
P0734 on Kia by Model
Kia Sorento(1 issue)
- AWD Coupling Failure and Grinding Noise2011-2020
The electronically-controlled AWD coupling (transfer case) in Sorentos fails due to worn clutch packs inside the coupling unit. The coupling is responsible for distributing torque to the rear wheels and uses a multi-plate clutch actuated by an electric motor. When the clutch packs wear out, the system cannot engage the rear axle properly, resulting in a grinding noise, vibration, and loss of AWD functionality. The coupling fluid also breaks down over time if not changed.
Kia Sportage(1 issue)
- 6-Speed Automatic (A6MF) Harsh Shifting and Valve Body Wear2017-2022
The A6MF-family 6-speed automatic can develop harsh or erratic shifting, hard 6-to-4 kickdown 'bang,' shift flares, brief neutral feel during up/downshifts, and torque-converter clutch (TCC) shudder. The root cause is wear of the reducing-valve bores in the valve body, which lets line pressure drift out of spec; neglected fluid (SP4-spec) accelerates the wear. A documented secondary fault is a valve-body bolt that can abrade the internal wiring harness, producing intermittent solenoid faults. This is a distinct transmission failure mode from the AWD rear-differential coupling noise already documented.
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What does P0734 mean on Kia?▼
P0734 stands for "Gear 4 Incorrect Ratio." This code means the Transmission/Powertrain Control Module detected an incorrect gear ratio in 4th gear. The module continuously compares input shaft speed to output shaft speed; if the ratio in 4th gear doesn't match the expected value, it sets P0734. This usually indicates the transmission is slipping or not fully engaging 4th gear due to a hydraulic, friction, or solenoid problem. Symptoms include slipping, flaring RPM, harsh or missed shifts, and possibly limp mode. On Kia specifically, this code is documented across 2 models.
What causes P0734 on Kia vehicles?▼
Common causes on Kia: Low or degraded/burnt transmission fluid, Slipping clutch packs or worn friction elements in 4th gear, Stuck or faulty shift solenoid, Valve body / internal hydraulic leak or restriction, Worn or failing torque converter. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0734 on a Kia?▼
Repair costs on Kia range from $400 to $2,500, depending on the specific model and root cause.
Which Kia models have P0734 documented?▼
Au7o has documented P0734 on 2 Kia models: Sorento, Sportage.