This procedure covers a minor tune-up for the 2016-2024 Hyundai Tucson 2.5L I4 AWD, including spark plug replacement, air filter replacement, and basic inspection of ignition components.

Warnings

Tools required

Parts

• Spark plugs (iridium) × 4 — 18855-11080 or equivalent NGK/Denso
• Engine air filter × 1 — 28113-D3300 or equivalent

Preparation

1. Ensure engine is completely cool to the touch (wait at least 2 hours after last operation)
2. Park vehicle on level ground and engage parking brake
3. Turn ignition to OFF position and remove key
4. Open hood and secure with prop rod
5. Gather all tools and replacement parts
6. Verify spark plug part numbers match vehicle specification

Procedure

1. 1

   Remove engine cover
   Locate the plastic engine cover on top of the 2.5L engine. Grasp firmly and pull upward to disengage the rubber grommets from their mounting posts. The cover is not bolted and should lift off with moderate upward pressure. Set aside in a clean area.
2. 2

   Remove air intake components
   Release the air box clips using a flathead screwdriver or by hand depending on clip style. Disconnect the mass airflow sensor electrical connector by pressing the tab and pulling away. Loosen the clamp at the throttle body connection and remove the intake tube. Lift the air box lid to access the air filter.
   Torque spec

   Air Box Clips5 Nm (4 lb-ft)
3. 3

   Replace engine air filter
   Remove the old air filter from the air box housing. Inspect the housing for debris, leaves, or moisture and clean if necessary using a shop towel. Install the new air filter ensuring the rubber seal seats properly around the perimeter of the housing. The filter should fit snugly without forcing.
4. 4

   Reinstall air intake system
   Close the air box lid and secure with clips. Reconnect the intake tube to the throttle body and tighten the clamp. Reconnect the mass airflow sensor electrical connector until it clicks into place. Ensure all connections are secure and properly seated.
   Torque spec

   Air Box Clips5 Nm (4 lb-ft)
5. 5

   Label and disconnect ignition coils
   Locate all four ignition coils on top of the valve cover. Each coil sits directly on a spark plug. Press the locking tab on each coil electrical connector and pull straight up to disconnect. Keep track of cylinder positions (cylinders numbered 1-4 from timing belt end to transmission end).
   ℹ️Labeling coil positions prevents incorrect reinstallation and potential misfires.
6. 6

   Remove ignition coils
   Using a 10mm socket, remove the single bolt securing each ignition coil to the valve cover. Pull each coil straight up with a firm twisting motion to break the seal. Inspect the coil boots for cracks, tears, or carbon tracking. Replace any damaged coils.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
7. 7

   Remove old spark plugs
   Using a 14mm spark plug socket with rubber insert and extension, carefully remove each spark plug. Turn counterclockwise and keep the socket straight to avoid cross-threading. Once loose, unthread by hand if possible. Inspect each plug for wear, fouling, or oil contamination which may indicate engine issues.
   ⚠Keep debris from falling into spark plug wells. Cover open wells with shop towels when not actively working on them.
8. 8

   Prepare and gap new spark plugs
   Remove new spark plugs from packaging. Verify gap specification (typically 0.039-0.043 inches for this engine, verify on plug box). Use gap gauge to confirm proper gap on each plug. Apply a small amount of anti-seize compound to the threads, avoiding the electrode end. Do not over-apply as excess can contaminate the combustion chamber.
9. 9

   Install new spark plugs
   Thread each spark plug by hand into its cylinder hole to prevent cross-threading. Once hand-tight, use the spark plug socket and torque wrench to tighten to 27 Nm (20 lb-ft). Install all four plugs using the same torque specification. Do not overtighten as this can damage the aluminum cylinder head threads.
   ⚠Cross-threading spark plugs will require expensive cylinder head repair. Always start threads by hand.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
10. 10

    Reinstall ignition coils
    Apply a thin coat of dielectric grease to the inside of each coil boot if desired (helps prevent moisture and eases future removal). Push each coil firmly onto its corresponding spark plug until fully seated. Reinstall the 10mm mounting bolt for each coil and torque to 27 Nm (20 lb-ft). Reconnect all electrical connectors until they click.
    Torque spec

    Mounting Bolts27 Nm (20 lb-ft)
11. 11

    Reinstall engine cover
    Align the engine cover mounting grommets with the posts on the engine. Press down firmly until all grommets snap into place. Ensure the cover sits flush and does not interfere with any hoses or wiring.

Reassembly

1. Verify all electrical connectors are fully seated and locked
2. Confirm no tools or shop towels are left in engine bay
3. Double-check that all ignition coil mounting bolts are installed

Verification

• Start the engine and verify it runs smoothly without misfires or rough idle
• Check for any unusual noises from the ignition system
• Verify no warning lights appear on the instrument cluster
• Allow engine to reach operating temperature and confirm smooth operation
• Perform a brief test drive to verify proper acceleration and no hesitation under load

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