🔧 Highlander - Ignition Coil Replacement

On your Highlander’s V6, there are 6 ignition coils (one per cylinder). The front 3 are easy to access, but the rear 3 sit under the upper intake manifold, so that part must come off to replace them.

Difficulty Level: Intermediate | Estimated Time: 2.5-4.5 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a cold engine to avoid burns.
• ⚠️ Disconnect the negative battery cable to prevent accidental shorts and misfires.
• ⚠️ Keep dirt out of the intake—cover openings with a clean rag once the manifold is removed.
• ⚠️ Don’t pull on wiring; release connector locks first.
• ⚠️ If any fuel smell is present after reassembly, stop and recheck hoses.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• 10mm socket
• 12mm socket
• 1/4" drive ratchet
• 3/8" drive ratchet
• 6" socket extension
• 10" socket extension
• Torque wrench (inch-pound)
• Torque wrench (foot-pound)
• Flathead screwdriver
• Trim clip removal tool
• Needle-nose pliers
• Pick tool
• Flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 6 (recommended: replace all six)
• Upper intake manifold gasket set - Qty: 1
• Throttle body gasket - Qty: 1
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and open the hood.
• Let the engine cool fully (intake parts get very hot).
• Disconnect the battery: use a 10mm socket to remove the negative terminal and tuck it aside.
• Quick question (so I tailor the steps): are you replacing one coil or all 6?

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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 to release it from the rubber grommets.
• Rock it gently; don’t yank.

Step 2: Remove the air intake tube (to make room)

• Use a flathead screwdriver to loosen the hose clamps on the intake tube.
• Unclip/unplug any small hoses or connectors in the way using needle-nose pliers and a trim clip removal tool.
• Lift the intake tube out and set it aside.

Step 3: Replace the FRONT bank ignition coils (easier side)

• Locate the 3 coils at the front of the engine (closest to the radiator).
• For each coil:
• Press the connector lock and unplug the coil using a pick tool gently if the tab is stubborn. A pick tool is a small hook used to lift tabs.
• Remove the coil hold-down bolt with a 10mm socket.
• Pull the coil straight up and out (twist slightly if stuck).
• Apply a tiny smear of dielectric grease inside the new coil boot (optional).
• Install the new coil fully seated, reinstall the bolt, and Torque to 9 Nm (80 in-lbf) using an inch-pound torque wrench.
• Plug the connector back in until it clicks.

Step 4: Prep for REAR bank access (upper intake manifold removal)

• Disconnect any electrical connectors and vacuum hoses attached to the upper intake manifold using a trim clip removal tool and needle-nose pliers.
• Label hoses with tape if you’re not 100% sure where they go. Photos help a lot.

Step 5: Remove the throttle body from the intake

• Unplug the throttle body connector (use a pick tool to lift the lock if needed).
• Remove the throttle body mounting bolts using a 10mm socket and 6" socket extension.
• Carefully move the throttle body aside (do not stress the wiring).
• Remove and discard the old gasket; you’ll install a new one later.
• When reinstalling later: Torque to 10 Nm (89 in-lbf).

Step 6: Remove the upper intake manifold

• Remove the upper intake manifold bolts with a 12mm socket, 3/8" drive ratchet, and 10" socket extension.
• Lift the manifold up and off carefully.
• Immediately cover the intake ports with clean rags so nothing falls in.
• Remove and discard the old upper intake gaskets.
• When reinstalling later: Torque to 21 Nm (15 ft-lbf) using a foot-pound torque wrench.

Step 7: Replace the REAR bank ignition coils

• Now you’ll see the 3 rear coils (closest to the firewall).
• Repeat the same coil procedure as the front bank:
• Unplug connector using a pick tool if needed.
• Remove hold-down bolt with a 10mm socket.
• Remove coil, install new coil, and Torque to 9 Nm (80 in-lbf).
• Reconnect each connector until it clicks.

Step 8: Reinstall the upper intake manifold

• Remove the rags from the intake ports.
• Install new upper intake manifold gaskets into their grooves.
• Set the manifold in place, start all bolts by hand.
• Tighten evenly, then Torque to 21 Nm (15 ft-lbf) using a foot-pound torque wrench.
• Reconnect all vacuum hoses and electrical connectors you removed.

Step 9: Reinstall the throttle body and intake tube

• Install a new throttle body gasket.
• Reinstall throttle body bolts with a 10mm socket, then Torque to 10 Nm (89 in-lbf).
• Plug the throttle body connector back in.
• Reinstall the air intake tube and tighten clamps with a flathead screwdriver.

Step 10: Reconnect the battery and reinstall the engine cover

• Reconnect the negative battery terminal using a 10mm socket.
• Reinstall the engine cover by pressing it down into the grommets.

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✅ After Repair

• Start the engine and let it idle for 2-3 minutes. It should be smooth.
• Listen for hissing (vacuum leak) around the intake manifold area.
• If the check engine light was on, clear codes with a scan tool and confirm they don’t return.
• Test drive 10-15 minutes and recheck for any warning lights.

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💰 DIY vs Shop Cost

Shop Cost: $450-$950 (parts + labor)

DIY Cost: $180-$550 (parts only)

You Save: $270-$400 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2.5-4.5 hours.

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🎯 Ready to get started?

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