🔧 Pathfinder - Spark Plug Replacement

On your Pathfinder, there are 6 spark plugs (one per cylinder). The front 3 are easy to reach, but the rear 3 sit under the upper intake plenum, so you’ll remove the upper intake to access them. Replacing worn plugs helps prevent misfires, rough idle, and poor fuel economy.

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

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and stripped threads.
• ⚠️ Disconnect the negative battery terminal before unplugging coils/sensors.
• ⚠️ Keep dirt out of the intake—cover ports with clean rags immediately.
• ⚠️ Do not drop anything into the intake runners; it can damage the engine.
• ⚠️ Use only hand tools on spark plugs; no impact tools.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 10mm socket
• 12mm socket
• 14mm spark plug socket
• 3/8" drive ratchet
• 3/8" drive extension set (3", 6", 10")
• 3/8" drive universal joint
• 1/4" drive ratchet
• 1/4" drive extension set
• Torque wrench (5-30 Nm range)
• Torque wrench (20-60 Nm range)
• Flat-blade screwdriver
• Hose clamp pliers
• Plastic trim tool
• Magnetic pickup tool
• Shop light
• Fender cover
• Compressed air blow gun

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (OEM-style, iridium) - Qty: 6
• Upper intake plenum 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.
• 🧰 Disconnect the negative battery terminal using a 10mm socket.
• 🧰 Take a quick photo of hoses and connectors before removal for easy reassembly.
• 🧰 Have clean rags ready to cover the intake ports once the upper intake comes off.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Pull up/remove the plastic engine cover (it’s retained by grommets on most setups).
• If yours has fasteners, remove them using a 10mm socket.

Step 2: Remove the air intake duct (to reach the throttle body area)

• Loosen the hose clamps using a flat-blade screwdriver.
• Disconnect any small breather hose(s) using hose clamp pliers.
• Lift the intake duct out and set it aside.

Step 3: Replace the front bank spark plugs (closest to radiator)

• Unplug each ignition coil electrical connector using a plastic trim tool to release the lock tab gently.
• Remove the coil hold-down bolt using a 10mm socket.
• Pull the coil straight up and out. Twist slightly to free the boot.
• Blow out the spark plug well using compressed air blow gun.
• Remove the spark plug using a 14mm spark plug socket, 3/8" drive ratchet, and 3/8" drive extension.
• Install the new plug by hand first (socket + extension only, no ratchet) to avoid cross-threading.
• Tighten with a torque wrench (5-30 Nm range): Torque to 18 Nm (13 ft-lbs).
• Apply a small smear of dielectric grease inside the coil boot (dielectric grease is a non-conductive grease that helps prevent moisture/corrosion).
• Reinstall the coil and bolt using a 10mm socket: Torque to 8 Nm (71 in-lbs).
• Reconnect the coil connector until it clicks.

Step 4: Remove components needed to access the upper intake plenum (rear bank)

• Unplug the throttle body connector using a plastic trim tool to release the lock tab.
• Disconnect vacuum/EVAP hoses from the upper intake using hose clamp pliers.
• Remove any brackets in the way using a 12mm socket.
• As you remove hoses, label them (masking tape works) so they go back to the same ports.

Step 5: Remove the throttle body (recommended for room)

• Remove the throttle body mounting bolts using a 10mm socket.
• Carefully separate it and remove the old gasket.
• Set the throttle body aside (do not stress the wiring).
• On reassembly, tighten throttle body bolts with a torque wrench (5-30 Nm range): Torque to 10 Nm (89 in-lbs).

Step 6: Remove the upper intake plenum (rear bank access)

• Remove the upper intake bolts/nuts using a 12mm socket (some locations may use 10mm socket depending on bracket points).
• Lift the plenum up and off. Use a magnetic pickup tool if a fastener is hard to grab.
• Immediately cover the exposed intake ports with clean rags.
• Remove and discard the old upper intake gaskets.
• On reassembly, tighten upper intake bolts/nuts with a torque wrench (20-60 Nm range): Torque to 25 Nm (18 ft-lbs).

Step 7: Replace the rear bank spark plugs (closest to firewall)

• Remove the rags one port area at a time so nothing can fall in.
• Unplug each ignition coil connector using a plastic trim tool.
• Remove each coil bolt using a 10mm socket, then pull the coil out.
• Blow out each plug well using compressed air blow gun.
• Remove each plug using a 14mm spark plug socket, 3/8" drive ratchet, 3/8" drive extensions, and a 3/8" drive universal joint as needed.
• Install each new plug by hand first, then tighten with a torque wrench (5-30 Nm range): Torque to 18 Nm (13 ft-lbs).
• Apply a small smear of dielectric grease inside each coil boot, reinstall coils, and tighten coil bolts: Torque to 8 Nm (71 in-lbs).
• Reconnect all coil connectors until they click.

Step 8: Reinstall the upper intake plenum and throttle body

• Install new upper intake gaskets in their grooves.
• Set the plenum in place and start all bolts/nuts by hand.
• Tighten evenly using a torque wrench (20-60 Nm range): Torque to 25 Nm (18 ft-lbs).
• Install the throttle body with a new gasket and tighten bolts: Torque to 10 Nm (89 in-lbs).
• Reconnect all vacuum/EVAP hoses using hose clamp pliers.
• Reconnect the throttle body connector.

Step 9: Reinstall the air intake duct and engine cover

• Reinstall the intake duct and tighten clamps using a flat-blade screwdriver.
• Reinstall any breather hoses using hose clamp pliers.
• Reinstall the engine cover.

Step 10: Reconnect the battery and do a final check

• Reconnect the negative battery terminal using a 10mm socket.
• Visually confirm: no leftover tools, all connectors clicked in, all hoses connected, no rags left in the intake.

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✅ After Repair

• ✅ Start the engine and let it idle for 1-2 minutes; it may stumble briefly as the throttle relearns.
• ✅ Check for air leaks (hissing), a check engine light, or rough idle.
• ✅ Take a short test drive and recheck for any loose clamps or fuel/air smell.

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💰 DIY vs Shop Cost

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

DIY Cost: $90-$220 (parts only)

You Save: $360-$630 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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