Replace spark plugs on the 2018-2024 Toyota Camry 2.5L I4 engine to restore ignition performance and maintain fuel efficiency.

Warnings

Tools required

Parts

• Spark plugs (iridium) × 4 — Toyota 90919-01253 or equivalent (Denso SK20R11)

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
4. Verify new spark plugs match OEM specification for this engine

Procedure

1. 1

   Remove engine cover
   Grasp the plastic engine cover firmly and pull upward to release the retaining clips. The cover is held by push clips only and does not require tools to remove. Set cover aside in a clean area.
2. 2

   Disconnect ignition coils
   Locate all four ignition coils on top of the engine. Press down on the locking tab of each coil electrical connector and pull straight up to disconnect. Mark or note the position of each coil if desired, though they are interchangeable.
3. 3

   Remove ignition coil bolts
   Using a 10mm socket, remove the single bolt securing each ignition coil. There is one bolt per coil. Keep bolts organized as they will be reused.
   Torque spec

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

   Extract ignition coils
   Grasp each ignition coil firmly and pull straight up with steady pressure to remove from the spark plug well. The coil boot may stick slightly due to heat cycling. If resistance is felt, twist gently while pulling. Inspect coil boots for cracks or damage.
5. 5

   Clean spark plug wells
   Use compressed air or a clean cloth to remove any debris, dirt, or oil from the spark plug wells before removing plugs. This prevents contaminants from entering the combustion chamber.
   ⚠If oil is present in spark plug wells, valve cover gaskets may need replacement
6. 6

   Remove old spark plugs
   Using the appropriate spark plug socket with extension, carefully loosen each spark plug by turning counterclockwise. Once loose, unthread by hand to prevent cross-threading. Remove all four plugs and inspect for abnormal wear, carbon buildup, or oil fouling which may indicate engine issues.
7. 7

   Inspect and gap new spark plugs
   Remove new spark plugs from packaging and verify the gap on each plug using a spark plug gap tool. Factory gap should be correct but always verify. Proper gap for this engine is typically 0.043 inches (1.1mm). Do not gap iridium plugs unless necessary as the electrode is fragile.
8. 8

   Apply anti-seize (optional)
   If using anti-seize compound, apply a small amount only to the threads of each spark plug, avoiding the electrode end. Use sparingly - a thin coat on the first 2-3 threads is sufficient. Some technicians skip this step on modern plugs with nickel-plated threads.
9. 9

   Install new spark plugs
   Carefully thread each new spark plug by hand into the cylinder head, turning clockwise. Thread at least 3-4 full turns by hand to ensure proper alignment and prevent cross-threading. Once hand-tight, use the torque wrench and spark plug socket to tighten to specification. Work slowly and carefully with the aluminum cylinder head.
   ⚠️Cross-threading or over-torquing spark plugs will damage aluminum cylinder head threads requiring expensive repair
   Torque spec

   Spark Plug20 Nm (15 lb-ft)
10. 10

    Reinstall ignition coils
    Apply a thin coat of dielectric grease to the inside of each coil boot if desired. Align each ignition coil over its corresponding spark plug and press down firmly until fully seated. The coil should sit flush with the valve cover surface.
11. 11

    Install ignition coil bolts
    Thread each ignition coil bolt by hand first, then tighten to specification using a torque wrench. Do not over-tighten as the valve cover is also aluminum.
    Torque spec

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

    Reconnect ignition coil connectors
    Push each electrical connector onto its corresponding ignition coil until you hear or feel a positive click indicating the locking tab has engaged. Gently pull on each connector to verify it is secure.
13. 13

    Reinstall engine cover
    Align the engine cover with the mounting clip locations and press down firmly on all clip positions until each clip snaps into place. Ensure the cover is fully seated and secure.

Reassembly

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

Verification

• Start the engine and listen for smooth idle with no misfires or rough running
• Check for any diagnostic trouble codes using an OBD-II scanner
• Allow engine to reach operating temperature and verify smooth acceleration
• Inspect for any unusual noises or vibrations that were not present before the service
• After first drive, check that engine cover and ignition coil connectors remain secure

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