🔧 IS - Ignition Coil Replacement

Your IS uses “coil-on-plug” ignition coils mounted on top of the engine. Replacing a bad coil fixes misfires, rough running, flashing check-engine light, and hesitation.

Difficulty Level: Beginner | Estimated Time: 0.5-1.0 hours

Assumption: stock coil-on-plug setup under the engine cover.

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⚠️ Safety & Precautions

• ⚠️ Let the engine fully cool; coils sit on a hot valve cover.
• ⚠️ Keep tools away from the battery positive terminal.
• ⚠️ Don’t pull on wiring; press connector locks and pull by the connector body.
• ⚠️ If you disconnect the battery, you may reset radio presets and adaptive memory.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 1/4" drive ratchet
• 3" socket extension (1/4")
• Torque wrench (in-lb capable)
• Trim clip removal tool
• Small flathead screwdriver
• Needle-nose pliers
• Shop flashlight
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 1-4
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Open the hood and let the engine cool completely.
• If you want maximum safety: use a 10mm socket to disconnect the negative battery terminal (optional).
• Dielectric grease is a silicone grease that helps prevent moisture/corrosion.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Use your hands to pull the plastic engine cover straight up to release it from the rubber grommets.
• If any clips or trim pieces block access on your cover: use a trim clip removal tool to lift them without cracking plastic.

Step 2: Unplug the ignition coil electrical connector

• Pick one coil to start with so you don’t mix anything up.
• Use a small flathead screwdriver to gently help lift the connector lock tab if it’s stuck, then pull the connector straight off.
• Do not pry hard—connectors break easily.

Step 3: Remove the coil hold-down bolt

• Use a 10mm socket, 3" socket extension (1/4"), and 1/4" drive ratchet to remove the single bolt holding the coil.
• Set the bolt aside where it won’t fall into the engine bay.

Step 4: Remove the ignition coil

• Twist the coil gently left-right to break the seal, then pull it straight up.
• If it’s stubborn, use steady upward force—don’t yank on the wiring.

Step 5: Install the new ignition coil

• Put a very small smear of dielectric grease inside the rubber boot of the new coil (the part that touches the spark plug).
• Align the coil and push it straight down until it seats fully on the spark plug.

Step 6: Reinstall the coil hold-down bolt

• Start the bolt by hand a few turns to avoid cross-threading.
• Use a 10mm socket, 3" socket extension (1/4"), and torque wrench (in-lb capable) to tighten the bolt.
• Torque to 10 Nm (89 in-lb)

Step 7: Plug the coil connector back in

• Push the connector on until you feel/hear a click.
• Gently tug-test it to confirm it’s locked.

Step 8: Repeat for the remaining coils

• Repeat Steps 2–7 for each remaining cylinder.
• Replace coils one-by-one to stay organized.

Step 9: Reinstall the engine cover

• Line up the cover with the grommets and press down firmly by hand until it snaps into place.
• If you disconnected the battery, reconnect it using a 10mm socket.

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✅ After Repair

• Start the engine and let it idle for 1–2 minutes. It should run smooth with no shaking.
• If the check-engine light was on: use an OBD-II scan tool (specialty) to clear codes and confirm the misfire does not return. (An OBD-II scan tool reads/clears fault codes from the car.)
• Test drive 10–15 minutes and recheck for warning lights.
• If you still have a misfire, the spark plugs or injector could be the cause (but coil replacement is the right first step when a coil code is present).

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💰 DIY vs Shop Cost

Shop Cost: $250-$650 (parts + labor)

DIY Cost: $60-$480 (parts only)

You Save: $190-$170 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.0 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.