Replacing the spark plugs on a 2015 Toyota Corolla is a straightforward process that can save you money on labor costs. Below is a step-by-step guide to help you perform this task efficiently.

Tools and Materials Needed

  • 10mm socket and ratchet for coil bolts
  • 14mm or 9/16" spark plug socket (preferably magnetized or with a rubber insert)
  • Ratchet with an extension bar
  • Torque wrench (optional but recommended)
  • Flathead screwdriver (for connector clips)
  • New spark plugs (OEM recommended: Denso or NGK Iridium)

Step-by-Step Instructions

1. Prepare the Vehicle

  • Ensure the engine is completely cool before starting.
  • Open the hood and locate the plastic engine cover. It is secured by four rubber grommets. Carefully lift it off by pulling at each corner.

2. Access the Ignition Coils

  • Identify the four ignition coils sitting above the spark plugs.
  • Disconnect the electrical connectors on each coil by pressing the tab and pulling gently. Use a flathead screwdriver if needed to release tight clips.

3. Remove the Ignition Coils

  • Use a 10mm socket to remove the bolt securing each coil.
  • Gently twist and pull the ignition coil straight out to avoid damaging the rubber boot.

4. Remove Old Spark Plugs

  • Insert your 14mm or 9/16" spark plug socket with an extension into the spark plug well.
  • Turn counterclockwise to loosen and remove the old spark plug. A magnetized socket or rubber insert will help lift it out easily.

5. Install New Spark Plugs

  • Carefully lower the new spark plug into the well using your socket. Avoid dropping it to prevent damage to the electrode.
  • Hand-tighten first, ensuring it threads evenly without cross-threading.
  • Use a torque wrench to tighten to 15 ft-lbs (20 Nm), or snug it securely without over-tightening.

6. Reinstall Ignition Coils

  • Place each ignition coil back into its position, aligning it properly with the spark plug.
  • Secure each coil with its 10mm bolt, tightening until snug.

7. Reconnect Electrical Connectors

  • Reattach the electrical connectors to each ignition coil until they click into place.

8. Replace Engine Cover

  • Align and press down on the plastic engine cover until it snaps back into place over its mounting points.

9. Final Check

  • Start the engine to ensure smooth operation. Listen for any unusual sounds that could indicate loose connections.

Tips for Success

  • Replace one spark plug at a time to avoid mixing up parts.
  • Use dielectric grease on connectors for easier removal in future maintenance.
  • Record this service in your vehicle’s maintenance log for reference.

FAQs About 2015 Toyota Corolla Spark Plugs Replacement

    • How often should I replace my spark plugs?
      The recommended interval is every 60,000–100,000 miles, depending on driving conditions and spark plug type.
    • What type of spark plugs should I use?
      Use OEM-recommended iridium spark plugs, such as Denso or NGK, for optimal performance.
    • Can I replace just one spark plug?
      It’s best to replace all four at once for consistent performance.