This procedure replaces the spark plugs on a 2016-2024 Hyundai Tucson 2.5L I4 engine. Note: This vehicle has a 4-cylinder engine, not a V6.

Warnings

Tools required

Parts

• Spark plugs (iridium or platinum) × 4 — Use OEM specification or equivalent NGK/Denso

Preparation

1. Ensure engine is completely cool to the touch (wait at least 2 hours after last operation).
2. Disconnect negative battery terminal to prevent accidental ignition system activation.
3. Remove engine cover by releasing clips and removing mounting bolts if equipped.
4. Clean debris from around ignition coil area using compressed air to prevent contamination of cylinders.

Procedure

1. 1

   Remove engine cover
   If equipped, carefully release the engine cover clips by pulling upward. Remove any mounting bolts securing the cover using a 10mm socket. Lift the cover away from the engine bay and set aside.
   Torque spec

   Engine Cover Clips3 Nm (2 lb-ft)

   Mounting Bolts27 Nm (20 lb-ft)
2. 2

   Disconnect ignition coil electrical connectors
   Locate all four ignition coils on top of the engine. Press the release tab on each coil connector and pull straight up to disconnect. Do not pull on wires, only on the connector body.
   ⚠Handle connectors gently to avoid breaking plastic tabs. Damaged connectors can cause misfires.
3. 3

   Remove ignition coils
   Remove the single bolt securing each ignition coil using a 10mm socket. Pull each coil straight up with a slight twisting motion to break the seal. If coils are stuck, gently wiggle while pulling upward. Set coils aside in order.
   Torque spec

   Ignition Coil Bolt11 Nm (8 lb-ft)
4. 4

   Clean spark plug wells
   Use compressed air or a vacuum to thoroughly clean around each spark plug well. Remove all dirt, debris, and oil. Ensure no foreign material can fall into the cylinders when plugs are removed.
   ⚠Any debris entering the cylinder will cause engine damage. Clean thoroughly before removing spark plugs.
5. 5

   Remove old spark plugs
   Using a spark plug socket with extension, carefully unthread each spark plug by turning counterclockwise. Once loose, remove by hand to prevent cross-threading. Inspect old plugs for wear patterns, oil fouling, or abnormal electrode wear.
   ℹ️Inspect old plugs for signs of engine issues: oil fouling indicates valve seal problems, white deposits suggest lean mixture, black deposits indicate rich mixture.
6. 6

   Prepare new spark plugs
   Verify spark plug gap matches specification (typically 0.039-0.043 inches for this engine, consult plug manufacturer). Apply a small amount of anti-seize compound to the threads, avoiding the electrode area. Use only a thin coating on the first 2-3 threads.
   ⚠Do not apply anti-seize to electrode or insulator. Keep anti-seize coating thin to prevent excess from entering combustion chamber.
7. 7

   Install new spark plugs
   Thread each new spark plug by hand into the cylinder head. Turn clockwise until finger-tight to ensure proper threading. If resistance is felt, stop immediately and verify plug is threading correctly. Never force a spark plug.
   ⚠️Cross-threading a spark plug in an aluminum head will destroy the threads and require costly helicoil repair. Always start by hand and ensure smooth threading.
8. 8

   Torque spark plugs to specification
   Using a torque wrench, tighten each spark plug to exactly 20.0 Nm (15.0 lb-ft). Use a smooth, steady motion. Do not exceed this torque value. Make one final pass to verify all plugs are torqued correctly.
   Torque spec

   Spark Plug20 Nm (15 lb-ft)
9. 9

   Reinstall ignition coils
   Apply a small amount of dielectric grease to the inside of each coil boot if desired. Push each coil firmly into place over its corresponding spark plug until fully seated. Install and hand-tighten the mounting bolt for each coil.
   ℹ️Dielectric grease prevents moisture intrusion and aids future removal but is optional.
10. 10

    Torque ignition coil bolts
    Using a torque wrench, tighten each ignition coil mounting bolt to 8.0 Nm (6.0 lb-ft). Do not over-torque as this can crack the coil housing.
    Torque spec

    Ignition Coil Bolt11 Nm (8 lb-ft)
11. 11

    Reconnect ignition coil connectors
    Reconnect each ignition coil electrical connector by pushing firmly until a click is heard. Gently tug each connector to verify it is securely latched.
    ⚠Ensure all connectors click into place. Loose connections will cause misfires and set diagnostic codes.
12. 12

    Reinstall engine cover and reconnect battery
    Position engine cover and secure mounting bolts to 27.0 Nm (20.0 lb-ft) and clips to 3.0 Nm (2.0 lb-ft) if applicable. Reconnect negative battery terminal. Clear any diagnostic codes if check engine light is illuminated.
    Torque spec

    Mounting Bolts27 Nm (20 lb-ft)

    Engine Cover Clips3 Nm (2 lb-ft)

Reassembly

1. Verify all electrical connectors are fully seated and latched.
2. Ensure no tools or parts are left in the engine bay.
3. Confirm engine cover is properly secured and all clips are engaged.

Verification

• Start the engine and listen for smooth idle with no misfires or rough running.
• Verify no check engine light or misfire codes are present after a 5-minute test drive.
• Inspect for any oil leaks around ignition coil boots after running engine.
• Confirm engine acceleration is smooth without hesitation or stumbling.

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