Replace spark plugs on a 2015 Kia Forte 1.8L I4 engine to restore proper ignition performance and fuel efficiency.

Warnings

Tools required

Parts

• Spark plugs × 4 — NGK 93221 or equivalent OEM spec

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level surface and engage parking brake
3. Gather all tools and new spark plugs before starting
4. Verify spark plug gap specification in owner's manual or on emissions label under hood

Procedure

1. 1

   Remove engine cover
   Grasp the engine cover firmly and pull upward to release the retaining clips. The cover is held by friction clips only and does not require tools on this model. Set cover aside in a clean area.
   Torque spec

   Engine Cover Clips3 Nm (2 lb-ft)
2. 2

   Disconnect ignition coils
   Locate the four ignition coils mounted directly above each spark plug. Press the release tab on each coil electrical connector and pull straight up to disconnect. Mark or note coil positions if desired, though they are interchangeable.
3. 3

   Remove ignition coils
   Using a 10mm socket, remove the single bolt securing each ignition coil. Pull each coil straight up with a gentle twisting motion to remove. Inspect coil boots for cracks or damage and replace if necessary.
   ℹ️Some coils may be tight due to rubber boot seal; avoid excessive force that could damage the coil
   Torque spec

   Ignition Coil Bolt10 Nm (8 lb-ft)
4. 4

   Clean spark plug wells
   Use compressed air or a clean cloth to remove any debris, dirt, or oil from around the spark plug wells. This prevents contamination from falling into the cylinders when plugs are removed.
   ⚠Do not allow debris to fall into the cylinder when spark plug is removed as this can cause engine damage
5. 5

   Remove old spark plugs
   Using the spark plug socket with extension, carefully remove each spark plug by turning counterclockwise. Remove plugs one at a time to avoid mixing up cylinder positions. Inspect old plugs for unusual wear, fouling, or damage which may indicate engine issues.
6. 6

   Prepare new spark plugs
   Using a spark plug gap tool, verify the gap on each new spark plug matches manufacturer specification (typically 0.039-0.043 inches for this engine). Apply a small amount of anti-seize compound to the threads of each spark plug, avoiding the electrode area.
   ⚠Use anti-seize sparingly; excess compound can cause fouling or enter the combustion chamber
   Torque spec

   Spark Plug19 Nm (14 lb-ft)
7. 7

   Install new spark plugs
   Thread each spark plug by hand into the cylinder head, ensuring it starts smoothly without cross-threading. Once hand-tight, use the torque wrench and spark plug socket to tighten to specification. Install one plug completely before moving to the next.
   ⚠️If spark plug does not thread smoothly by hand, STOP and investigate. Cross-threading will destroy aluminum cylinder head threads
   Torque spec

   Spark Plug19 Nm (14 lb-ft)
8. 8

   Reinstall ignition coils
   Apply a thin coat 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 tighten the retaining bolt on each coil.
   Torque spec

   Ignition Coil Bolt10 Nm (8 lb-ft)
9. 9

   Reconnect coil connectors
   Reconnect the electrical connector to each ignition coil, ensuring each connector clicks securely into place. Verify all connections are fully seated.
10. 10

    Reinstall engine cover
    Position the engine cover over the engine and press down firmly at each clip location until all clips engage with an audible snap. Verify cover is secure and sits flush.
    Torque spec

    Engine Cover Clips3 Nm (2 lb-ft)

Reassembly

1. Double-check that all ignition coil electrical connectors are fully seated and locked
2. Ensure engine cover is properly clipped in place at all mounting points
3. Verify no tools or parts were left in the engine compartment

Verification

• Start the engine and verify it runs smoothly without misfires or rough idle
• Check for proper engine operation with no check engine light illumination
• Listen for any unusual sounds that might indicate improper installation
• Test drive vehicle and confirm normal acceleration and performance

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