This procedure replaces the input speed sensor on the automatic transmission of a 2015 Kia Forte with 1.8L I4 engine, requiring access from underneath the vehicle.

Warnings

Tools required

Parts

• Input speed sensor × 1 — Use OEM specification
• Sensor O-ring seal × 1 — Often included with sensor

Fluids

• Kia SP-IV-M ATF — 0.5 qt

Preparation

1. Park vehicle on level ground and apply parking brake
2. Place wheel chocks behind rear wheels
3. Raise front of vehicle and support securely on jack stands
4. Remove driver side front wheel for better access (optional but recommended)
5. Disconnect negative battery terminal to prevent electrical issues
6. Allow transmission to cool to ambient temperature if recently driven

Procedure

1. 1

   Locate the input speed sensor
   From underneath the vehicle, locate the input speed sensor on the left side of the transmission case, near the front. It will have an electrical connector attached and is positioned above the transmission pan. The input sensor is typically closer to the engine than the output sensor.
2. 2

   Disconnect electrical connector
   Press the locking tab on the electrical connector and carefully pull it straight off the sensor. If the connector is stuck due to corrosion, gently work it side to side while pulling. Do not pull on the wiring harness itself.
3. 3

   Position drain pan
   Place a drain pan directly beneath the sensor location. Expect approximately 0.25 to 0.5 quarts of ATF to drain when the sensor is removed, depending on fluid level and vehicle position.
4. 4

   Remove sensor mounting bolt
   Using a 10mm socket, remove the single bolt securing the input speed sensor to the transmission case. Keep this bolt as it will be reused.
   Torque spec

   Sensor Bolts10 Nm (8 lb-ft)
5. 5

   Extract the sensor
   Carefully pull the sensor straight out of the transmission case. It may require slight twisting or rocking motion to break the O-ring seal. Allow residual ATF to drain into the pan. Inspect the old sensor for metal debris on the magnetic tip, which could indicate internal transmission wear.
6. 6

   Clean the mounting bore
   Wipe the sensor mounting bore in the transmission case with a clean shop towel. Remove any old O-ring material or debris. Do not allow dirt or contaminants to enter the transmission case.
   ⚠Keep the mounting bore area clean to prevent contamination of the transmission fluid.
7. 7

   Prepare new sensor
   Inspect the new input speed sensor and verify it matches the old unit. Check that a new O-ring is installed on the sensor body. If provided separately, install the new O-ring into the groove on the sensor. Lightly coat the O-ring with clean ATF for easier installation.
8. 8

   Install new sensor
   Carefully insert the new input speed sensor straight into the transmission case bore, ensuring the O-ring does not roll or pinch. Push the sensor in until it seats flush against the transmission case mounting surface.
9. 9

   Install and torque mounting bolt
   Install the sensor mounting bolt and tighten by hand until snug. Using a torque wrench, tighten the bolt to specification. Do not overtighten as this can crack the sensor body.
   ⚠Overtightening the sensor bolt can crack the plastic sensor housing and cause immediate failure.
   Torque spec

   Sensor Bolts10 Nm (8 lb-ft)
10. 10

    Reconnect electrical connector
    Inspect the electrical connector for corrosion or damage. Optionally spray electrical contact cleaner into the connector and allow to dry. Push the connector firmly onto the sensor until the locking tab clicks into place. Tug gently to verify it is secure.
11. 11

    Check and refill transmission fluid
    Measure the amount of ATF that drained and add an equivalent amount of Kia SP-IV-M ATF through the transmission dipstick tube. Start the engine and allow it to reach operating temperature. With the engine running and transmission in Park, check the fluid level and add as needed to bring to the proper level on the dipstick.

Reassembly

1. Reinstall driver side front wheel if removed and torque lug nuts to specification
2. Reconnect negative battery terminal
3. Lower vehicle from jack stands

Verification

• Start the engine and verify no ATF leaks around the sensor
• Use an OBD-II scanner to verify the input speed sensor is reading properly and no DTCs are present
• Test drive the vehicle and confirm smooth shifting with no transmission-related warning lights
• Recheck transmission fluid level after test drive and top off if necessary

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