🔧 Tacoma - Spark Plug Replacement

On your Tacoma’s 4.0L V6, the spark plugs sit under the ignition coils. Three plugs are easy to reach, and the other three usually require removing the upper intake manifold so you can access the rear/driver-side bank.

Difficulty Level: Intermediate | Estimated Time: 2.5-4.0 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and stripped plug threads.
• ⚠️ Keep dirt out of the intake—cover openings with a clean rag when the intake is off.
• ⚠️ Do not over-tighten spark plugs; the cylinder heads are aluminum.
• ⚠️ Battery disconnect is recommended to prevent accidental shorts while unplugging coils/throttle body.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 12mm socket
• 1/4" drive ratchet
• 3/8" drive ratchet
• 3/8" drive torque wrench (5-80 ft-lbs range)
• 6" extension (3/8")
• 10" extension (3/8")
• 3/8" universal joint
• 5/8" spark plug socket (3/8")
• Flat-blade screwdriver
• Needle-nose pliers
• Trim clip removal tool
• Compressed air blow gun
• Shop vacuum
• Clean shop rags
• Flashlight
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (correct fit for 4.0L V6) - Qty: 6
• 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, 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.
• Lay out 6 new plugs and keep them clean; don’t drop them.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover and intake tube

• Remove the engine cover using a 10mm socket (if equipped).
• Loosen the intake hose clamps using a flat-blade screwdriver.
• Unclip/unplug the intake duct connections as needed using needle-nose pliers and a trim clip removal tool.
• Lift the intake tube/air duct out and set it aside.

Step 2: Replace the easy-to-access spark plugs (front/passenger-side bank)

• Unplug one ignition coil connector at a time (press the tab and pull).
• Remove the coil hold-down bolt with a 10mm socket, then pull the coil straight up.
• Blow out the spark plug well using a compressed air blow gun so debris can’t fall into the cylinder.
• Remove the spark plug using a 5/8" spark plug socket (3/8") with a 6" extension (3/8") and 3/8" drive ratchet.
• Install the new plug by lowering it in with the 5/8" spark plug socket (3/8") and extension, then start threading by hand only.
• Use a 3/8" drive torque wrench (5-80 ft-lbs range) to tighten: Torque to 18 Nm (13 ft-lbs).
• Apply a tiny amount of dielectric grease inside the coil boot. Keep grease off plug threads.
• Reinstall the coil and tighten the coil bolt: Torque to 10 Nm (89 in-lbs).
• Repeat for the other accessible plugs on this bank.

Step 3: Remove the throttle body (to access the upper intake manifold)

• Unplug the throttle body electrical connector.
• Remove the throttle body mounting bolts/nuts using a 10mm socket.
• Carefully pull the throttle body off and remove the old gasket.
• Cover the opening with a clean rag so nothing falls in.

Step 4: Remove the upper intake manifold

• Label any vacuum hoses/connectors you remove so they go back to the same place.
• Disconnect vacuum lines and hose clamps using needle-nose pliers and a flat-blade screwdriver.
• Remove the upper intake manifold bolts/nuts using a 12mm socket with a 3/8" drive ratchet and 10" extension (3/8").
• Lift the upper intake manifold off carefully.
• Immediately stuff clean rags into the intake ports. Nothing falls in, nothing breaks.
• Remove the old intake gaskets and clean the mating surfaces using a clean shop rag and shop vacuum.

Step 5: Replace the remaining spark plugs (rear/driver-side bank)

• Unplug each coil connector and remove the coil bolt using a 10mm socket.
• Pull the coil straight out.
• Blow out each plug well using the compressed air blow gun.
• Remove each plug using the 5/8" spark plug socket (3/8"), 3/8" universal joint, extensions, and 3/8" drive ratchet as needed.
• A universal joint is a swivel adapter for tight angles.
• Install each new plug by hand first, then tighten with the torque wrench: Torque to 18 Nm (13 ft-lbs).
• Reinstall coils and tighten coil bolts: Torque to 10 Nm (89 in-lbs).
• A torque wrench tightens to an exact setting.

Step 6: Reinstall the upper intake manifold with new gaskets

• Install the new upper intake manifold gaskets in the correct positions.
• Remove the rags from the intake ports and double-check nothing is left behind using a flashlight.
• Set the upper intake manifold back in place.
• Hand-start all bolts/nuts, then tighten evenly using a 12mm socket and 3/8" drive ratchet.
• Tighten final using the 3/8" drive torque wrench (5-80 ft-lbs range): Torque to 21 Nm (15 ft-lbs).
• Reconnect all vacuum lines and electrical connectors.

Step 7: Reinstall the throttle body with a new gasket

• Install the new throttle body gasket.
• Reinstall the throttle body and hand-start bolts/nuts.
• Tighten using a 10mm socket, then final torque with the torque wrench: Torque to 10 Nm (89 in-lbs).
• Plug the throttle body connector back in.

Step 8: Reinstall the intake tube and engine cover

• Reinstall the intake tube and tighten hose clamps using a flat-blade screwdriver.
• Reinstall any clips using the trim clip removal tool.
• Reinstall the engine cover using a 10mm socket.

Step 9: 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 for 2–3 minutes; the idle may be slightly high at first.
• Listen for a hissing sound (vacuum leak) and watch for a check engine light.
• Do a short test drive, then re-check for any loose clamps or connectors.
• If you get a misfire code after the job, re-check that each coil connector is fully seated and each coil bolt is tight.

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💰 DIY vs Shop Cost

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

DIY Cost: $70-$180 (parts only)

You Save: $180-$480 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2.5-4.0 hours.

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🎯 Ready to get started?

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