🔧 Spark Plugs - Replacement

Your Corolla uses four iridium spark plugs. Replacing them restores smooth idle, clean acceleration, and helps prevent misfires or rough running. On this engine, the job is straightforward if you work on a cold engine and keep the coil boots clean.

Difficulty Level: Intermediate | Estimated Time: 1-2 hours

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⚠️ Safety & Precautions

• Let the engine cool completely before starting. Hot aluminum threads can be damaged easily.
• Do not drop dirt into the spark plug wells.
• Handle the ignition coils gently. They are the black coil packs on top of the engine.
• Battery disconnect is not required, but disconnecting the negative terminal adds safety if you want extra protection.
• Use the correct torque on the plugs. Overtightening can strip the cylinder head.

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🔧 Required Tools

You'll need the following tools for this repair:

• 3/8-inch drive ratchet
• 10mm socket
• 8mm socket
• 5/8-inch spark plug socket
• 3-inch extension
• 6-inch extension
• Torque wrench
• Plastic trim tool
• Compressed air
• Dielectric grease
• Anti-seize compound
• Safety glasses
• Gloves

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plug set - Qty: 4
• Ignition coil boots - Qty: 4, replace if cracked or oil-soaked
• Throttle body gasket - Qty: 1, only if removed for access

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Make sure the engine is completely cold.
• Open the hood and remove any loose items from the engine bay.
• If the engine cover is installed, remove it first.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Use your hands or a plastic trim tool to lift the engine cover straight up.
• Set it aside safely.

Step 2: Disconnect the ignition coil connectors

• Press the lock tab on each coil connector and unplug it.
• Work one coil at a time so you do not mix anything up.
• Small connector tab, gentle pressure.

Step 3: Remove the ignition coils

• Use a 10mm socket and ratchet to remove the coil hold-down bolts.
• Pull each coil straight up and out of the spark plug well.
• If a coil sticks, twist it slightly while lifting.

Step 4: Clean around each spark plug well

• Use compressed air to blow dirt away from each plug well.
• This keeps debris from falling into the cylinder.
• Clean first, remove later.

Step 5: Remove the old spark plugs

• Use a 5/8-inch spark plug socket, extension, and ratchet to remove each plug.
• Turn counterclockwise to loosen.
• Lift each plug out carefully.

Step 6: Check and prepare the new plugs

• Compare each new plug to the old one before installation.
• Install the plugs dry unless the plug maker says otherwise.
• If needed, use a tiny amount of anti-seize compound only if the plug manufacturer allows it; many iridium plugs do not need it.

Step 7: Install the new spark plugs

• Start each plug by hand using the spark plug socket and extension only.
• Thread them in carefully to avoid cross-threading.
• Use a torque wrench to torque each plug to 18 Nm (13 ft-lbs).

Step 8: Reinstall the ignition coils

• Add a small amount of dielectric grease inside each coil boot if desired.
• Slide each coil straight down onto the new plug.
• Reinstall the hold-down bolts with a 10mm socket.
• Torque to 9 Nm (80 in-lbs).

Step 9: Reconnect the coil connectors and reassemble

• Push each connector back onto its coil until it clicks.
• Reinstall the engine cover.
• Make sure no tools are left in the engine bay.

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✅ After Repair

• Start the engine and let it idle.
• Listen for smooth idle and watch for the check engine light.
• If the engine shakes or misfires, recheck coil connectors and plug torque.
• Take a short test drive and confirm normal acceleration.

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💰 DIY vs Shop Cost

Shop Cost: $220-$420 (parts + labor)

DIY Cost: $45-$120 (parts only)

You Save: $175-$300 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1-2 hours.

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🎯 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.