Kia Forte P0730: Meaning, causes and diagnosis


P0730 Kia Forte

P0730 is a standard OBD2 fault code. Indicates that your Kia Forte’s PCM has detected an incorrect gear ratio.

Although this code may appear if you change the transmission or rear gear in your Forte without restarting the computer, it almost always has nothing to do with an incorrect gear ratio.

It is almost always caused by an internal transmission problem. However, P0730 will appear if the transmission fluid is low or dirty.

Before doing anything, check your Forte’s transmission fluid (on a flat surface). If it’s low, refill it, and if it’s dirty, change it. That is the most common solution for P0730.

Definition of P0730P0730 Definition: Kia Forte

The PCM in your Kia Forte measures the speed of the input shaft and output shaft and compares them to each other. If their rotation speeds are further apart than the computer allows, P0730 will be activated.

P0730 Symptoms: Kia Forte

These are the most common symptoms associated with P0730:

  • Transmission slip: Your Taomca does not accelerate, but the RPM increases without a corresponding increase in speed.
  • Does not shift gears correctly: It may not shift properly due to an internal transmission problem, or it may be in “limp” mode.
  • check engine light: Make sure you grab any other codes that appear and cross-reference them with P0730
  • Lower fuel consumption: If the transmission does not shift smoothly and at the proper time, it may decrease your fuel mileage.

It is not very common for there to be no noticeable symptoms with P0730.

Kia Forte P0730 Causes

P0730 Diagnostic

Here are the most common causes of P0730 and a proper order of diagnostic operations to check them.

Check the transmission fluid

Check the transmission fluid before doing anything else. If your Forte is low on transmission fluid, fill it up and see if it starts shifting and driving like it should. Also, check the color of the transmission fluid. If the fluid is burnt, it will not do its job as well as hydraulic fluid.

Here is a transmission fluid color chart to compare yours:

Transmission fluid color

If the color of your transmission fluid is anything other than maroon and you have the P0730 code, changing it can clear the code.

A dirty transmission fluid filter can prevent pressure from building properly, which can cause slippage and throw the code.

Listen when you drive

Drive your Forte at highway speeds and pay attention to the engine RPM. The RPM should be constant on a traditional automatic transmission if you are not increasing throttle load

If the RPM increases at the slightest extra throttle (but only a few hundred revs), that could indicate a bad torque converter clutch. This condition usually triggers P0740. If you have P0740, solving the cause of this code should cause P0730 to disappear along with it. If it increases more than that, it is likely an internal transmission problem.

If the RPM is bouncing or increasing much more than the vehicle speed, that would indicate slippage, and you will need to take it to a transmission shop. But before doing so, check that the wiring from the transmission to the TCM is not damaged, which could be causing the P0730.

Check the wiring

Check the wiring between your Forte’s transmission control module and the transmission for damage. Look for corroded or shorted cables. Sometimes road debris can damage the harness.

Internal transmission problems

Although repairing internal transmission problems is best left to repair professionals, here are the most likely internal transmission problems that can cause P0730:

  • Worn pump
  • Torque converter clutch or clutch solenoid failure
  • Clogged transmission control
  • Faulty shift solenoid or shift solenoid wiring
  • defective TCM


Although there are many potential problems that can cause P0730 on the Kia Forte, the most common solution is to treat the transmission fluid.


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