This procedure covers the removal and replacement of the knock sensor on a 2015 Kia Forte with the 1.8L I4 engine. The knock sensor is located on the engine block beneath the intake manifold.

Warnings

Tools required

Parts

• Knock sensor × 1 — Use OEM specification
• Intake manifold gasket (if damaged) × 1 — Use OEM specification

Preparation

1. Ensure engine is completely cool to the touch
2. Disconnect the negative battery terminal and wait 3 minutes
3. Remove the engine cover by pulling upward on the front clips
4. Release fuel system pressure if disturbing any fuel lines during access

Procedure

1. 1

   Remove air intake components
   Disconnect the air intake tube from the throttle body by loosening the hose clamp. Remove the air filter housing assembly by disconnecting the breather hoses and unbolting the mounting hardware. Set aside to provide working clearance.
2. 2

   Disconnect electrical connectors and vacuum lines
   Disconnect the electrical connectors from the throttle body, fuel injectors, and any sensors on the intake manifold. Label or photograph connections for reassembly reference. Disconnect vacuum lines from the intake manifold, noting their routing.
3. 3

   Remove throttle body
   Remove the four bolts securing the throttle body to the intake manifold using a 12mm socket. Carefully pull the throttle body away from the manifold and set aside with gasket. Cover the intake opening with a clean shop towel to prevent debris entry.
   Torque spec

   Mounting Bolts45 Nm (33 lb-ft)
4. 4

   Disconnect fuel rail
   Disconnect the fuel supply line from the fuel rail by pressing the quick-disconnect release tabs. Remove the two bolts securing the fuel rail using a 10mm socket. Carefully lift the fuel rail with injectors attached and secure it out of the way without stressing the injector harness.
   ⚠Have shop towels ready to catch any residual fuel. Ensure adequate ventilation and no ignition sources nearby.
5. 5

   Remove intake manifold support brackets
   Remove the support bracket bolts connecting the intake manifold to the engine block and cylinder head using a 14mm socket. These brackets are typically located on the sides and rear of the manifold. Note bracket positions for proper reinstallation.
   Torque spec

   Mounting Bolts45 Nm (33 lb-ft)
6. 6

   Remove intake manifold
   Remove all intake manifold mounting bolts in reverse of the tightening sequence (work from outside to center) using a 12mm or 14mm socket as applicable. Carefully lift the intake manifold straight up and away from the cylinder head. Inspect and remove the gasket. Cover the intake ports with clean shop towels.
   ℹ️The manifold may be stuck to the gasket. Gently pry at the designated pry points only—never between sealing surfaces.
   Torque spec

   Gasket Bolts19 Nm (14 lb-ft)
7. 7

   Locate and access knock sensor
   The knock sensor is located on the engine block below where the intake manifold was mounted, typically on the driver's side of the block between cylinders 2 and 3. It has a single wire connector. Clean the area around the sensor of any debris or oil buildup.
8. 8

   Disconnect knock sensor electrical connector
   Press the locking tab on the knock sensor electrical connector and carefully pull the connector straight off the sensor. Inspect the connector and pins for corrosion or damage. Clean if necessary with electrical contact cleaner.
9. 9

   Remove knock sensor
   Using a 12mm socket with extension, carefully remove the knock sensor bolt by turning counterclockwise. Remove the knock sensor from the engine block. Note the orientation and position for proper installation of the new sensor.
10. 10

    Install new knock sensor
    Clean the knock sensor mounting hole in the engine block with a clean shop towel. Install the new knock sensor by hand, ensuring it seats flat against the mounting surface. Using a torque wrench with 12mm socket, tighten the knock sensor to specification. This torque value is critical for proper sensor function.
    ⚠Do not over-torque the knock sensor. Excessive torque will damage the sensor element and cause false readings. Use a calibrated torque wrench.
    Torque spec

    Knock Sensor20 Nm (15 lb-ft)
11. 11

    Reconnect knock sensor connector
    Push the electrical connector firmly onto the knock sensor until the locking tab clicks into place. Gently tug on the connector to verify it is secured. Route the wiring away from heat sources and sharp edges.
12. 12

    Reinstall intake manifold
    Remove shop towels from intake ports. Install a new intake manifold gasket on the cylinder head, aligning all port openings. Carefully position the intake manifold onto the gasket, ensuring proper alignment. Install all mounting bolts hand-tight, then torque in sequence from center outward to specification.
    ℹ️Follow the proper tightening sequence to ensure even gasket compression and prevent vacuum leaks. Typically tighten center bolts first, then work outward.
    Torque spec

    Gasket Bolts19 Nm (14 lb-ft)
13. 13

    Reinstall remaining components
    Reinstall the intake manifold support brackets and torque bolts to specification. Reinstall the fuel rail and injectors, securing with mounting bolts. Reconnect the fuel supply line until it clicks. Install the throttle body with a new gasket if needed and torque mounting bolts to specification. Reconnect all vacuum lines, electrical connectors, and breather hoses per earlier labeling.
    Torque spec

    Mounting Bolts45 Nm (33 lb-ft)
14. 14

    Reinstall air intake system
    Reinstall the air filter housing assembly and secure all mounting hardware. Reconnect the air intake tube to the throttle body and tighten the hose clamp. Ensure all clips and connections are secure. Reinstall the engine cover.
15. 15

    Reconnect battery and clear codes
    Reconnect the negative battery terminal. Using an OBD-II scanner, clear any stored knock sensor diagnostic trouble codes. Start the engine and verify no vacuum leaks are present by listening for hissing sounds and checking for smooth idle.

Reassembly

1. Double-check that all electrical connectors, vacuum lines, and fuel lines are properly secured
2. Verify all intake manifold bolts are torqued to specification in the proper sequence
3. Ensure no tools or shop towels were left in the engine compartment

Verification

• Start the engine and listen for smooth operation with no vacuum leaks or unusual noises
• Allow the engine to reach operating temperature and verify the cooling fans cycle properly
• Use an OBD-II scanner to verify no knock sensor codes are present (P0325, P0326, P0327, P0328)
• Test drive the vehicle under light acceleration to confirm normal engine performance and no detonation
• Verify no fuel leaks are present around the fuel rail connections
• Check for proper throttle response and idle quality

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