🔧 Spark Plugs - Replacement

Your Sequoia uses eight individual coil-on-plug ignition coils, so the job is straightforward but a little tight around the intake and front accessories. Replacing all eight plugs at the same time helps restore smooth idle, fuel economy, and cold-start performance.

Difficulty Level: Intermediate | Estimated Time: 2-4 hours

---

⚠️ Safety & Precautions

• Let the engine cool completely before starting; spark plugs thread into aluminum cylinder heads.
• Disconnect the negative battery cable before removing ignition coils.
• Do not drop anything into the spark plug wells or intake openings.
• Use only the correct spark plug type and gap for the 5.7L V8.
• Do not over-tighten the plugs; the cylinder heads can be damaged easily.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 3/8-inch drive ratchet
• 10mm socket
• 12mm socket
• 14mm socket
• 5/8-inch spark plug socket
• 3-inch extension
• 6-inch extension
• Torque wrench
• Flat trim tool
• Needle-nose pliers
• Dielectric grease
• Anti-seize compound
• Safety glasses
• Mechanic gloves

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plug set - Qty: 8
• Valve cover gasket set - Qty: 1
• Ignition coil boots - Qty: 8

---

📋 Before You Begin

• Park on level ground and set the parking brake.
• Make sure the engine is cold.
• Disconnect the negative battery cable with a 10mm socket.
• Remove the engine cover and any intake ducting that blocks access.
• Label connectors so they go back in the same spot.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover and intake ducting

• Use a 10mm socket or pull up on the engine cover if equipped with snap-on mounts.
• If the air duct blocks access, loosen the clamps with a flat tool and remove the ducting.

Step 2: Disconnect the battery

• Use a 10mm socket to remove the negative battery cable.
• Move the cable aside so it cannot spring back and touch the terminal.

Step 3: Remove the ignition coils

• Use a 10mm socket to remove the coil hold-down bolts.
• Unplug each coil connector by pressing the lock tab and pulling straight off.
• Lift each coil straight up. If it sticks, gently twist it first.
• Keep the coils in order if you plan to reuse them.

Step 4: Remove the old spark plugs

• Use a 5/8-inch spark plug socket, ratchet, and extension to loosen each plug.
• Turn each plug out slowly and keep the socket straight so the plug does not bind.
• Inspect each old plug for heavy oil, white deposits, or broken electrodes.

Step 5: Prepare and install the new spark plugs

• Check that each new plug matches the correct spec before installation.
• If needed, apply a tiny amount of anti-seize compound only to the threads. Do not get any on the electrode.
• Start each plug by hand using the spark plug socket and extension.
• Tighten each plug with a torque wrench to 18 N·m (13 ft-lbs).
• Start every plug by hand first.

Step 6: Reinstall the ignition coils

• Apply a small amount of dielectric grease inside each coil boot.
• Push each coil straight down onto its plug until fully seated.
• Install the coil bolts with a 10mm socket.
• Tighten the coil bolts snugly to 9 N·m (80 in-lbs).
• Reconnect each coil electrical connector until it clicks.

Step 7: Reassemble the intake and engine cover

• Reinstall any intake ducting and tighten the clamps with a flat tool.
• Reinstall the engine cover.
• Reconnect the negative battery cable with a 10mm socket.

---

✅ After Repair

• Start the engine and let it idle for a few minutes.
• Listen for misfires, ticking, or air leaks around the intake.
• Check that the check engine light stays off.
• If the engine runs rough, recheck each coil connector and plug socket seating.

---

💰 DIY vs Shop Cost

Shop Cost: $450-$850 (parts + labor)

DIY Cost: $120-$260 (parts only)

You Save: $330-$590 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2-4 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.