Replace all four spark plugs on the 2015 Kia Forte 1.8L I4 engine to maintain proper ignition and engine performance.

Warnings

Tools required

Parts

• Spark plug (NGK or equivalent OEM specification) × 4 — Use OEM specification

Preparation

1. Park vehicle on level ground and engage parking brake.
2. Turn ignition off and remove key from ignition.
3. Allow engine to cool for at least 30 minutes if recently operated.
4. Open hood and secure with prop rod.

Procedure

1. 1

   Remove engine cover
   Remove the plastic engine cover by releasing any clips and removing the cover screws. Lift the cover straight up to disengage from mounting grommets.
   Torque spec

   Cover Screws10 Nm (8 lb-ft)

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

   Disconnect first ignition coil
   Locate the ignition coil on cylinder 1 (nearest to timing belt end). Press the locking tab on the electrical connector and pull straight up to disconnect the coil connector.
   ℹ️Label or photograph connector positions if needed to ensure correct reassembly.
3. 3

   Remove first ignition coil
   Remove the ignition coil mounting bolt using a 10mm socket. Gently twist and pull the coil straight up to remove it from the spark plug well. Inspect the coil boot for damage or oil contamination.
   Torque spec

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

   Remove old spark plug from cylinder 1
   Use compressed air or a clean rag to remove any debris from around the spark plug well. Insert spark plug socket with extension and carefully unthread the spark plug. Remove the plug and inspect for abnormal wear, fouling, or damage.
   ⚠Prevent debris from falling into the cylinder. If debris enters, it must be removed before installing new plug.
5. 5

   Prepare new spark plug
   Check the gap on the new spark plug using a gap tool and verify it matches manufacturer specification (typically 0.039-0.043 inches for this engine). If using anti-seize, apply a very small amount only to the threads, avoiding the electrode area.
   ℹ️Excessive anti-seize can cause over-torquing and thread damage. Use sparingly or omit entirely on new plugs.
   Torque spec

   Spark Plug19 Nm (14 lb-ft)
6. 6

   Install new spark plug in cylinder 1
   Carefully thread the new spark plug by hand into the cylinder head to ensure proper thread engagement. Once hand-tight, use the torque wrench and spark plug socket to tighten to specification.
   ⚠If plug does not thread easily by hand, stop and reposition to avoid cross-threading.
   Torque spec

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

   Reinstall first ignition coil
   Apply a thin coat of dielectric grease to the inside of the coil boot if desired. Push the coil firmly onto the spark plug until it seats completely. Install and torque the coil mounting bolt, then reconnect the electrical connector until it clicks.
   Torque spec

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

   Repeat for remaining cylinders
   Repeat steps 2 through 7 for cylinders 2, 3, and 4, working from front to back of the engine. Complete one cylinder at a time to avoid mixing up coils or leaving a cylinder without a plug.
   Torque spec

   Ignition Coil Bolt10 Nm (8 lb-ft)

   Spark Plug19 Nm (14 lb-ft)
9. 9

   Reinstall engine cover
   Position the engine cover over the mounting grommets and press down firmly to seat. Install and tighten the cover screws and engage any clips to specification.
   Torque spec

   Cover Screws10 Nm (8 lb-ft)

   Engine Cover Clips3 Nm (2 lb-ft)

Reassembly

1. Ensure all ignition coil electrical connectors are fully seated and locked.
2. Verify all ignition coil mounting bolts are properly torqued.
3. Confirm engine cover is securely fastened with all clips engaged.

Verification

• Start the engine and verify smooth idle with no misfires or rough running.
• Check for diagnostic trouble codes using an OBD-II scanner; clear any stored codes if necessary.
• Listen for any unusual noises or vibrations that might indicate improper installation.
• Verify no fuel smell or visible spark arcing around ignition coils during operation.

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