🔧 Ignition Coils - Replacement

Your Corolla uses four coil-on-plug ignition coils mounted directly on top of the spark plugs. Replacing a bad coil can fix misfires, rough idle, hesitation, and check engine light codes like P0301-P0304.

Difficulty Level: Beginner | Estimated Time: 0.5-1 hour

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⚠️ Safety & Precautions

• Let the engine cool completely before starting.
• Ignition coils carry high voltage, so do not touch the coil terminals with the key on.
• Disconnect the negative battery cable if you want extra safety while unplugging the coils.
• Keep dirt out of the spark plug wells.
• Work on one coil at a time.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 1/4-inch ratchet
• 6-inch extension
• Trim panel tool
• Torque wrench
• Needle-nose pliers
• Gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 1-4, replace as needed or replace all four
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Turn the ignition off and remove the key or fob from the car.
• Open the hood and let the engine cool.
• If disconnecting the battery, remove the negative cable first using a 10mm socket.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Lift the plastic engine cover straight up by hand.
• If it feels stuck, gently pry up with a trim panel tool.

Step 2: Unplug the ignition coil connector

• Find the coil on top of the engine near each spark plug.
• Press the connector lock tab and pull the plug straight off by hand.
• Do not pull on the wires.

Step 3: Remove the coil retaining bolt

• Use a 10mm socket, 1/4-inch ratchet, and 6-inch extension to remove the coil bolt.
• Keep the bolt in a safe place.

Step 4: Remove the ignition coil

• Twist the coil slightly and pull it straight up by hand.
• If it is stuck, wiggle it gently while pulling upward.
• Inspect the rubber boot for oil, cracks, or tearing.

Step 5: Install the new ignition coil

• Apply a small amount of dielectric grease inside the coil boot if desired.
• Push the new coil straight down into the spark plug tube until fully seated.
• Install the coil bolt by hand first.
• Use a torque wrench to tighten the coil bolt to 9 Nm (80 in-lbs).

Step 6: Reconnect the electrical connector

• Push the connector on until it clicks.
• Make sure the lock tab is fully seated.

Step 7: Reinstall the engine cover

• Line up the cover and press it down firmly by hand.

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✅ After Repair

• Start the engine and listen for smooth idle.
• Check that the check engine light is off.
• If the light stays on, scan for misfire codes.
• If you replaced one coil due to a misfire, road test the car and make sure the engine runs clean under load.

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💰 DIY vs Shop Cost

Shop Cost: $180-$450 (parts + labor)

DIY Cost: $40-$220 (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 0.5-1 hour.

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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.