A transmission fluid pressure test is performed to determine the condition of the hydraulic components and whether there are any leaks

  • 1. Set the parking brake and chock the front and rear wheels
  • 2. Start the engine until the gearbox is warmed up to a temperature of 60~70°C.
  • 3. Before testing, check the levels of all operating fluids and, if necessary, bring them to normal.
  • 4. Connect a tachometer to the engine.
  • 5. Remove the mudguard on the left side under the front bumper.

KIA RIO automatic transmission oil pressure check

  • 6. Connect a pressure gauge OK201 190 AA0 to the pressure test port. To access the fitting, it is advisable to raise the car.

Performing testing

  • 1. Start the engine.

KIA RIO automatic transmission oil pressure check

  • 2. Check the engine speed at idle and in selector position "P".

Engine idle speed:

For Europe and Australia: 750-850 min-1

Total: 700-800 min-1

  • 3. Move the selector lever to position "D" and read the pressure on the pressure gauge.

To prevent damage to the gearbox, complete steps 4 and 5 within 5 seconds.

  • 4. Press the brake pedal all the way down with your left foot, and gently press the accelerator pedal with your right foot.
  • 5. When the engine speed no longer increases, read the pressure on the pressure gauge and release the accelerator pedal.

Running the engine for at least one minute at idle speed cools the transmission fluid and prevents deterioration.

Before each subsequent test, allow sufficient time to cool the gearbox.

  • 6. With the engine running, move the selector lever to position N and let the engine run at idling speed for at least one minute.
  • 7. Similarly, measure the pressure in all positions of the selector lever:

Transmission fluid pressure, kPa


At idle

In stall test mode

D, 2,1






  • 8. Remove the pressure gauge and close the fitting with a stopper.

Tightening torque: 5.0 - 9.8 Nm

Assessing the results of the transmission fluid pressure test

Transmission fluid pressure

Location of possible malfunction

Low pressure in each selector lever position

Oil pump worn out

Leaks in the oil pump, control valve and/or gearbox housing

Pressure regulator valve blocked

Low pressure in positions D and 2 only

Transmission fluid leaks in hydraulic forward clutch

Low pressure in R position only

Transmission fluid leaks in hydraulic clutch

Lower forward and reverse or reverse clutch

Pressure higher than specification

Pressure regulator valve or inline solenoid valve blocked