🔧 Highlander - Ignition Coil Replacement

Replacing the ignition coils on your Highlander is a straightforward engine-top repair. The ignition coils sit directly on top of the spark plugs and create the high voltage needed to fire each cylinder.

Difficulty Level: Beginner | Estimated Time: 30-60 minutes

---

⚠️ Safety & Precautions

• ⚠️ Let the engine cool completely before starting. Hot aluminum and plastic parts can burn you.
• ⚠️ Disconnect the negative battery cable before unplugging ignition coils to reduce the chance of electrical shorts.
• ⚠️ Work gently around plastic connectors. Older Toyota connectors can become brittle.
• ⚠️ Do not drop dirt or debris into the spark plug wells. The spark plug well is the deep tube where each coil sits.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 3/8-inch drive ratchet
• 3-inch socket extension
• 10mm wrench
• Torque wrench rated in inch-pounds
• Flat trim tool
• Compressed air duster
• Shop towels
• Nitrile gloves
• Safety glasses

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

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

Tip: Replace only the failed coil unless all coils are high-mileage or original.

---

📋 Before You Begin

• Park your Highlander on level ground and shift to Park.
• Set the parking brake.
• Open the hood and allow the engine to cool.
• If replacing only one coil, match the new coil to the cylinder that has the misfire code.
• Common misfire codes match cylinders like this: P0301 = cylinder 1, P0302 = cylinder 2, P0303 = cylinder 3, P0304 = cylinder 4.
• The 2.7L inline-4 has all four ignition coils accessible on top of the engine.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Disconnect the Battery

• Put on safety glasses and nitrile gloves.
• Use a 10mm wrench to loosen the nut on the negative battery terminal.
• Lift the negative cable off the battery post and move it aside so it cannot spring back.
• Black cable is usually negative.

Step 2: Remove the Engine Cover

• If your Highlander has a plastic engine cover, lift it straight up by hand.
• If it feels stuck, use a flat trim tool gently near the rubber mounting points.
• Set the cover aside where it will not get stepped on.

Step 3: Clean Around the Coils

• Use a compressed air duster to blow dust and grit away from the top of the ignition coils.
• Use shop towels to wipe around each coil area.
• This keeps dirt from falling into the spark plug wells when the coils are removed.

Step 4: Unplug the Ignition Coil Connector

• Choose the ignition coil you are replacing.
• Press the locking tab on the electrical connector with your thumb.
• Pull the connector straight back from the coil.
• If it is stubborn, use a flat trim tool to gently help release the tab.
• Do not pull on the wires themselves.

Step 5: Remove the Ignition Coil Bolt

• Use a 10mm socket, 3-inch socket extension, and 3/8-inch drive ratchet to remove the coil hold-down bolt.
• Place the bolt somewhere safe.
• The hold-down bolt is the small bolt that keeps the coil from lifting out.

Step 6: Remove the Old Ignition Coil

• Grip the ignition coil body by hand.
• Twist it gently left and right to break the rubber boot loose.
• Pull the coil straight upward out of the spark plug well.
• Check the rubber boot for oil, coolant, burning, swelling, or cracks.
• If the spark plug well has oil inside, the valve cover tube seal may also need repair.

Step 7: Prepare the New Ignition Coil

• Compare the new ignition coil with the old one to make sure the shape and connector match.
• Apply a very small amount of dielectric grease packet inside the end of the rubber boot.
• Dielectric grease is a non-conductive silicone grease that helps seal out moisture and makes future removal easier.
• Do not pack the boot full of grease.

Step 8: Install the New Ignition Coil

• Slide the new ignition coil straight down into the spark plug well by hand.
• Push until you feel the boot seat onto the spark plug.
• Install the hold-down bolt by hand first to avoid cross-threading.
• Use a 10mm socket, 3-inch socket extension, and torque wrench rated in inch-pounds to tighten the bolt.
• Torque to 8 Nm (71 in-lbs)

Step 9: Reconnect the Electrical Connector

• Push the electrical connector straight onto the ignition coil until it clicks.
• Lightly tug on the connector by hand to confirm it is locked.
• Repeat Steps 4-9 for any additional coils you are replacing.

Step 10: Reinstall the Engine Cover

• Line up the plastic engine cover with its mounting points.
• Press it down by hand until it seats evenly.
• Make sure no wires or hoses are trapped under the cover.

Step 11: Reconnect the Battery

• Place the negative battery cable back onto the battery post.
• Use a 10mm wrench to tighten the terminal nut until snug.
• Do not overtighten the battery terminal.

---

✅ After Repair

• Start your Highlander and let it idle for 1-2 minutes.
• Listen for smooth idle and check that the engine does not shake.
• If a check engine light was on, it may turn off after several drive cycles, or it can be cleared with a scan tool.
• Take a short test drive and confirm the hesitation, rough idle, or misfire is gone.
• If the same cylinder misfire returns, inspect the spark plug, wiring connector, and fuel injector for that cylinder.

---

💰 DIY vs Shop Cost

Shop Cost: $180-$500 per coil area repair depending on diagnosis, parts, and labor

DIY Cost: $45-$130 per ignition coil

You Save: $100-$350 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.

---

🎯 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.