🔧 Tacoma - Spark Plug Replacement

On your Tacoma’s 4.0L V6, each spark plug sits deep in a “spark plug tube” under an ignition coil. The job is straightforward, but the driver-side plugs are tight—removing the upper intake plenum makes it much easier for a first-timer.

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

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⚠️ Safety & Precautions

• 🛑 Work on a fully cool engine to avoid burns and stripped plug threads.
• 🛑 Disconnect the negative battery cable before unplugging coils.
• 🛑 Keep dirt out of the engine—blow out plug wells before removing plugs.
• 🛑 Do not use anti-seize on iridium plugs (they’re coated).

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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
• 3/8" drive ratchet
• 3/8" drive extension set (3", 6", 10")
• 3/8" drive wobble extension
• 3/8" drive universal joint
• 5/8" spark plug socket
• Torque wrench (ft-lb, 10-30 ft-lb range)
• Torque wrench (in-lb, 50-150 in-lb range)
• Flathead screwdriver
• Needle-nose pliers
• Trim clip tool
• Compressed air blow gun
• Flashlight
• Shop towels

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (pre-gapped) - Qty: 6
• Upper intake plenum gasket - 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 chock the rear wheels.
• 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 photos of hoses before removal.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover and intake duct

• If equipped, remove the engine cover using a 10mm socket.
• Loosen the intake tube clamps using a flathead screwdriver.
• Disconnect any small breather/vacuum hoses using needle-nose pliers as needed (squeeze the clamp, slide it back).
• Lift the intake tube/air duct out and set it aside.

Step 2: Unplug and remove the easy-access ignition coils

• On the passenger side, locate the ignition coils (one per cylinder) on top of the valve cover.
• Press the electrical connector tab and unplug each coil connector.
• Remove each coil hold-down bolt using a 10mm socket.
• Twist the coil slightly to break the seal, then pull it straight up.
• Torque for coil bolts on reassembly: Torque to 9 N·m (80 in-lb)
• If a connector is stuck, don’t yank wires.

Step 3: Remove the throttle body (for access)

• Unplug the throttle body electrical connector.
• Remove the throttle body mounting bolts using a 10mm socket.
• Carefully pull the throttle body away and set it aside with shop towels (avoid stressing any attached lines).
• Torque for throttle body bolts on reassembly: Torque to 10 N·m (89 in-lb)

Step 4: Remove the upper intake plenum (recommended for driver-side plug access)

• Disconnect vacuum hoses and any brackets attached to the upper plenum using needle-nose pliers and a 10mm socket.
• Remove the upper intake plenum mounting bolts using a 12mm socket with a 3/8" ratchet and extensions.
• Lift the upper plenum up and off.
• Immediately stuff clean shop towels into the exposed intake openings to prevent anything from falling in.
• Torque for upper plenum bolts on reassembly: Torque to 21 N·m (15 ft-lb)

Step 5: Remove the remaining ignition coils

• With the plenum out of the way, unplug the driver-side coil connectors.
• Remove the coil hold-down bolts using a 10mm socket.
• Pull the coils straight up and set them in order (so they go back where they came from).

Step 6: Clean the spark plug wells

• Use compressed air to blow dirt out of each spark plug tube before removing the plug.
• Wear safety glasses because debris can fly back.

Step 7: Remove the old spark plugs

• Install a 5/8" spark plug socket on a 3/8" ratchet with the needed extension(s).
• For tight angles, use a wobble extension or universal joint.
• Break the plug loose, then spin it out by hand with the ratchet.
• Lift the plug out with the spark plug socket.

Step 8: Install the new spark plugs

• Confirm the new plugs are iridium and pre-gapped to 1.1 mm (0.043 in) (do not bend the fine iridium tip).
• Start each plug by hand using the spark plug socket and extension only (no ratchet at first) to avoid cross-threading.
• Tighten with a torque wrench.
• Torque spark plugs: Torque to 18 N·m (13 ft-lb)
• If it doesn’t thread smoothly, stop.

Step 9: Reinstall coils and apply a small amount of dielectric grease

• Put a small dab of dielectric grease inside each coil boot (the rubber spark plug “sock”).
• Push the coil straight down until it fully seats on the plug.
• Install the coil bolt using a 10mm socket, then tighten with an in-lb torque wrench.
• Torque to 9 N·m (80 in-lb)
• Plug the electrical connectors back in until they click.

Step 10: Reassemble the intake and throttle body

• Remove the shop towels from the intake openings.
• Install the new upper plenum gasket, set the plenum in place, and start all bolts by hand.
• Tighten plenum bolts evenly using a 12mm socket.
• Torque to 21 N·m (15 ft-lb)
• Install the new throttle body gasket, reinstall the throttle body using a 10mm socket.
• Torque to 10 N·m (89 in-lb)
• Reconnect all vacuum/breather hoses and electrical connectors.
• Reinstall the intake duct and tighten the clamps using a flathead screwdriver.

Step 11: Reconnect battery

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

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✅ After Repair

• Turn the key to ON for 10 seconds, then start the engine and let it idle.
• Listen for vacuum leaks (hissing) and watch for a check engine light.
• Do a short test drive and re-check that all clamps/hoses are secure.
• Rough idle usually means a missed connector.

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💰 DIY vs Shop Cost

Shop Cost: $350-$650 (parts + labor)

DIY Cost: $60-$140 (parts only)

You Save: $210-$590 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2-3 hours.

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🎯 Ready to get started?

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