🔧 Spark Plug Replacement - Replacement

Your Corolla uses four coil-on-plug spark plugs under the ignition coils. The job is straightforward, but you need to work carefully so you do not crack a coil, strip the plug threads, or drop debris into the cylinders.

Difficulty Level: Beginner | Estimated Time: 1.5-2.5 hours

---

⚠️ Safety & Precautions

• Work on a cool engine only. Hot aluminum threads can be damaged easily.
• Disconnect the negative battery cable before removing ignition coils.
• Keep dirt out of the spark plug wells. Debris can fall into the engine.
• Do not overtighten the spark plugs. The cylinder head is aluminum.
• If a coil boot is torn, replace the ignition coil or boot before reassembly.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 3/8-inch ratchet
• 6-inch extension
• Spark plug socket, 5/8-inch
• Torque wrench
• Gap gauge
• Dielectric grease
• Trim clip tool
• Safety glasses
• Gloves

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs - Qty: 4
• Dielectric grease - Qty: 1

---

📋 Before You Begin

• Park on level ground and set the parking brake.
• Let the engine cool completely.
• Turn the ignition off and remove the key or keep the fob away from the vehicle.
• Disconnect the negative battery terminal before touching the ignition coils.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Lift the plastic engine cover straight up by hand. On some cars, it may take a firm pull.
• Pull straight up, not at an angle.

Step 2: Disconnect the battery

• Use a 10mm socket to remove the negative battery cable.
• Move the cable aside so it cannot spring back and touch the terminal.

Step 3: Remove the ignition coil bolts

• Use a 10mm socket and 3/8-inch ratchet to remove the four coil hold-down bolts.
• Keep the bolts in order so they go back in the same spots.
• Torque on reassembly: 9 N·m (80 in-lbs)

Step 4: Remove the ignition coils

• Pull each ignition coil straight up by hand.
• If a coil is stuck, twist it gently while pulling up.
• Do not pry against the valve cover.

Step 5: Remove the spark plugs

• Use a 5/8-inch spark plug socket, 6-inch extension, and 3/8-inch ratchet to remove each spark plug.
• Turn each plug counterclockwise slowly.
• If a plug feels tight, back it out carefully to avoid thread damage.

Step 6: Check the new plugs

• Compare the new plugs to the old ones.
• Check the gap with a gap gauge. Many iridium plugs come pre-gapped.
• If adjustment is needed, make only tiny changes.

Step 7: Install the new spark plugs

• Thread each plug in by hand first using the spark plug socket and extension.
• This helps prevent cross-threading.
• Once seated, tighten with a torque wrench to 18 N·m (13 ft-lbs).
• Hand-start every plug first.

Step 8: Reinstall the ignition coils

• Add a small amount of dielectric grease inside each coil boot.
• Push each coil straight down onto its plug.
• Reinstall the coil bolts with a 10mm socket and tighten to 9 N·m (80 in-lbs).

Step 9: Reconnect the battery and reinstall the cover

• Reconnect the negative battery cable with a 10mm socket.
• Reinstall the engine cover by pressing it down evenly.

---

✅ After Repair

• Start the engine and let it idle.
• Listen for a smooth idle with no misfire or clicking.
• If the check engine light is on, scan for codes and clear them if the repair fixed the issue.
• Take a short test drive and confirm normal acceleration.

---

💰 DIY vs Shop Cost

Shop Cost: $180-$320 (parts + labor)

DIY Cost: $40-$90 (parts only)

You Save: $140-$230 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.5 hours.

---

🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.