This procedure covers the removal and replacement of spark plug wires (ignition coil connectors) on the 2016-2024 Hyundai Tucson 2.5L I4 AWD engine, which uses individual coil-on-plug ignition.

Warnings

Tools required

Parts

• Spark plugs (4) × 4 — Use OEM specification - Hyundai 18855-10080 or equivalent
• Ignition coil connectors (if damaged) × 4 — Inspect existing connectors

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level surface and engage parking brake
3. Disconnect negative battery terminal and wait 3 minutes for airbag system to discharge
4. Remove engine cover by pulling upward on clips (no tools required on most models)

Procedure

1. 1

   Access ignition coils
   Locate the four ignition coils on top of the engine. They are positioned directly above each spark plug. Clear any debris from the valve cover area using compressed air to prevent contamination from entering the spark plug wells.
2. 2

   Disconnect ignition coil electrical connectors
   Press down on the locking tab of each ignition coil connector and pull straight up to disconnect. The connectors have a positive lock mechanism. Note the routing of each connector for proper reinstallation.
   ⚠Do not pull on the wires themselves. Always grasp the connector body to avoid damaging the wiring harness.
3. 3

   Remove ignition coil hold-down bolts
   Using a 10mm socket, remove the single bolt securing each ignition coil. Keep bolts organized by cylinder position. Some models may have a slightly different bolt configuration, so verify bolt type before removal.
4. 4

   Remove ignition coils
   Grasp each ignition coil firmly and pull straight up with a twisting motion to break the seal. The coil boot may be stuck in the spark plug well due to heat cycling. Use steady pressure and avoid excessive force that could damage the coil or boot.
   ⚠If a coil boot remains stuck in the spark plug well, use a boot removal tool or needle-nose pliers to extract it carefully.
5. 5

   Clean spark plug wells
   Use compressed air or brake cleaner to remove any debris, oil, or dirt from each spark plug well. Ensure the area around each spark plug is completely clean before removal to prevent contamination from entering the combustion chamber.
6. 6

   Remove old spark plugs
   Using a spark plug socket with extension, carefully remove each spark plug by turning counterclockwise. Note the condition of each plug for diagnostic purposes. If plugs are difficult to remove, apply penetrating oil and wait 15 minutes before attempting removal again.
   ⚠Remove spark plugs in a smooth, controlled motion. Cross-threading or binding may indicate debris in threads or damaged threads.
7. 7

   Inspect and gap new spark plugs
   Verify that new spark plugs match OEM specifications. Check and adjust the electrode gap to 0.039-0.043 inches (1.0-1.1mm) using a gap tool. Even new plugs should be verified as they may shift during shipping.
   ℹ️The 2.5L Smartstream engine requires iridium spark plugs. Do not use standard copper plugs as a substitute.
8. 8

   Apply anti-seize and install spark plugs
   Apply a small amount of anti-seize compound to the threads of each new spark plug, avoiding the electrode area. Thread each spark plug by hand into the cylinder head to prevent cross-threading. Once hand-tight, use the torque wrench to tighten to specification.
   ⚠️CRITICAL: Do not exceed 20 Nm (15 lb-ft) torque specification. The aluminum cylinder head threads are easily damaged by over-torquing.
   Torque spec

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

   Prepare ignition coil boots
   Inspect each ignition coil boot for cracks, tears, or carbon tracking. Apply a thin layer of dielectric grease inside each boot to ensure proper sealing and prevent moisture intrusion. This also aids in future removal.
10. 10

    Install ignition coils
    Carefully insert each ignition coil into its respective spark plug well, ensuring proper alignment with the spark plug terminal. Press down firmly until the coil seats completely on the valve cover. Install and hand-tighten the hold-down bolt for each coil.
11. 11

    Torque ignition coil bolts
    Using a torque wrench, tighten each ignition coil bolt to the specified torque. Work in a sequence from cylinder 1 to cylinder 4 to ensure even installation.
    Torque spec

    Ignition Coil Bolt11 Nm (8 lb-ft)
12. 12

    Reconnect electrical connectors
    Push each ignition coil electrical connector onto its corresponding coil until you hear and feel a positive click. Gently tug on each connector to verify it is fully seated and locked in place. Route wiring to avoid contact with hot engine components.
13. 13

    Reinstall engine cover and battery
    If engine cover was secured with bolts, torque to specification. If clip-type, press down firmly on clip locations until they snap into place. Reconnect the negative battery terminal.
    Torque spec

    Engine Cover Clips3 Nm (2 lb-ft)

Reassembly

1. Ensure all four ignition coil connectors are fully seated and locked
2. Verify engine cover is properly secured and all clips are engaged
3. Double-check that no tools or materials were left in the engine bay

Verification

• Turn ignition to ON position (do not start) and verify no check engine light or ignition system warnings appear
• Start the engine and verify smooth idle with no misfires or rough running
• Listen for any unusual sounds from the ignition coils or plug wells
• Allow engine to reach operating temperature and verify stable operation under light acceleration
• Use an OBD-II scanner to check for any pending misfire codes (P0300-P0304)
• Verify there are no fuel or burning smells from the engine compartment

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