🔧 Sequoia - Spark Plug Replacement

Your Sequoia uses 8 ignition coils (one per cylinder) and long-life iridium spark plugs. The job is mostly about careful access, keeping debris out of the cylinders, and torquing the new plugs correctly.

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

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⚠️ Safety & Precautions

• 🔥 Work on a fully cool engine to avoid burns and prevent thread damage.
• 🔋 Disconnect the negative battery terminal before unplugging ignition coils.
• 🧼 Blow dirt away from each spark plug well before removing the plug, so nothing falls into the cylinder.
• 🧵 Start spark plugs by hand first to avoid cross-threading the aluminum cylinder head.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 14mm socket
• 3/8" ratchet
• 5/8" spark plug socket
• 6" extension (3/8")
• 12" extension (3/8")
• 3/8" universal joint
• Torque wrench (3/8", 10-30 Nm range)
• Trim clip removal tool
• Flathead screwdriver
• Needle-nose pliers
• Compressed air blow gun
• Shop vacuum
• Clean shop rags
• Nitrile gloves
• Safety glasses
• Wiper arm puller (specialty)

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (OEM-equivalent) - Qty: 8
• 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.
• Use a 10mm socket to disconnect the negative battery terminal and isolate it so it can’t spring back.
• Take a photo before unplugging anything.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Remove the plastic engine cover (if equipped) by releasing it from its mounts; if bolts are present, use a 10mm socket.
• Set the cover aside where it won’t get stepped on.

Step 2: Create working room (intake duct area)

• Loosen any intake duct clamps as needed using a flathead screwdriver.
• Move the ducting aside gently (you’re just making room to reach coils more comfortably).
• If it fights you, re-check for hidden clips.

Step 3: Decide if you need extra rear access (cowl removal)

• If you can comfortably reach the rear-most coils, skip to Step 4.
• If your hands/tools can’t reach the rear plugs, remove the wiper/cowl pieces below.

Step 3A: Remove wiper arms (only if needed for rear access)

• Flip up the small caps at the base of each wiper arm using a flathead screwdriver.
• Remove the wiper arm nuts using a 14mm socket.
• If the arm is stuck on the tapered shaft, use a wiper arm puller (specialty) to lift it off.

Step 3B: Remove the cowl top panel (only if needed)

• Remove the plastic clips using a trim clip removal tool.
• Remove any small bolts using a 10mm socket.
• Lift off the cowl panel carefully and set it aside.

Step 4: Unplug and remove one ignition coil (do one cylinder at a time)

• Locate an ignition coil and press the connector lock tab, then unplug it by hand (use needle-nose pliers gently only if needed).
• Remove the coil hold-down bolt using a 10mm socket.
• Twist the coil boot slightly and pull the coil straight up and out.
• Torque on reassembly: Torque to 10 Nm (89 in-lbs)
• Keep each coil with its cylinder.

Step 5: Clean the spark plug well

• Use a shop vacuum to remove loose dirt around the spark plug tube.
• Use compressed air blow gun to blow out the spark plug well so debris can’t fall into the cylinder.
• Wear safety glasses while using compressed air.

Step 6: Remove the old spark plug

• Install the 5/8" spark plug socket on a 6" extension (3/8") (add the 3/8" universal joint and/or 12" extension (3/8") as needed for angle/reach).
• Use the 3/8" ratchet to loosen and remove the spark plug.
• Pull the plug out with the socket and inspect it (oil on threads, heavy deposits, damaged electrode).

Step 7: Install the new spark plug (hand-start first)

• Put the new plug into the 5/8" spark plug socket so it’s held straight.
• Lower it into the well and turn it clockwise by hand using only the extension (no ratchet yet) until it seats. This helps prevent cross-threading.
• Torque the spark plug using a torque wrench (3/8", 10-30 Nm range): Torque to 18 Nm (13 ft-lbs)
• Don’t change the gap on iridium plugs.

Step 8: Reinstall the ignition coil

• Apply a very small amount of dielectric grease inside the coil boot (this helps prevent sticking and moisture intrusion).
• Push the coil straight down until it fully seats on the spark plug.
• Install the coil bolt using a 10mm socket, then Torque to 10 Nm (89 in-lbs) with the torque wrench (3/8", 10-30 Nm range).
• Reconnect the electrical connector until it clicks.

Step 9: Repeat for all 8 cylinders

• Repeat Steps 4 through 8 for each remaining cylinder, one at a time.
• One-at-a-time prevents mixing connectors.

Step 10: Reassemble intake/cowl parts (if removed)

• Reinstall any intake ducting and tighten clamps using a flathead screwdriver.
• If removed, reinstall the cowl panel using a 10mm socket and clips with a trim clip removal tool.
• If removed, reinstall wiper arms and nuts using a 14mm socket and snug them firmly.

Step 11: Reconnect the battery

• Reconnect the negative battery terminal using a 10mm socket.

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✅ After Repair

• Start the engine and let it idle. It should run smooth with no shaking.
• Listen for ticking/hissing near the valve covers (could indicate a loose plug or coil not seated).
• If you have a check engine light or misfire, re-check each coil connector is fully clicked in.
• Take a short test drive and confirm normal power and no warning lights.

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💰 DIY vs Shop Cost

Shop Cost: ₹12,000-₹25,000 (parts + labor)

DIY Cost: ₹4,000-₹10,000 (parts only)

You Save: ₹8,000-₹15,000 by doing it yourself!

Shop labor rates vary but typically run ₹800-₹1,500/hour. This repair takes a shop approximately 2-3 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.