🔧 Wrangler - Spark Plug Replacement

On your Wrangler’s 3.6L V6, the spark plugs sit under the ignition coils. The passenger-side plugs are fairly open, but the driver-side plugs are tight and usually require removing the upper intake manifold to reach them safely.

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 threads.
• ⚠️ Disconnect the negative battery cable before unplugging coils/sensors.
• ⚠️ Keep debris out of the intake ports—stuff clean rags in ports if the intake manifold is removed.
• ⚠️ Do not over-tighten spark plugs; aluminum heads strip easily.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 10mm socket
• 8mm socket
• 1/4" drive ratchet
• 3/8" drive ratchet
• 3/8" drive torque wrench (10-30 ft-lbs range)
• 5/8" spark plug socket
• 6" extension (3/8")
• 12" extension (3/8")
• 3/8" universal joint
• Flat trim tool
• Pick tool
• Compressed air blow gun
• Feeler gauge (0.043")
• Magnetic pickup tool

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (OEM-style iridium, pre-gapped) - Qty: 6
• Upper intake manifold gasket set - 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 cable and isolate it.
• Lay out 6 plugs in order and work one cylinder at a time to avoid mixing parts.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover and intake tube

• Pull up on the engine cover to release it (it’s held by rubber grommets).
• Use an 8mm socket to loosen the intake tube clamps.
• Unclip/remove any breather hose using a flat trim tool, then lift the intake tube out.

Step 2: Remove ignition coils on the easy-access bank (passenger side)

• Unplug each coil electrical connector using a pick tool to lift the lock, then pull the connector off. (A lock tab is a small safety clip that prevents unplugging.)
• Remove the coil bolt with a 10mm socket.
• Twist the coil gently and pull it straight up and out.

Step 3: Remove the passenger-side spark plugs

• Blow out the spark plug wells using compressed air blow gun so dirt can’t fall into the cylinder.
• Remove each plug using a 5/8" spark plug socket, 6" extension (3/8"), and 3/8" drive ratchet.
• Check the new plug gap with a feeler gauge (0.043"). Don’t force-bend iridium tips.
• Install the new plug by hand first using the spark plug socket and extension (no ratchet at first) to avoid cross-threading.
• Tighten with a torque wrench: Torque to 18 Nm (13 ft-lbs).

Step 4: Remove the upper intake manifold (to reach driver-side plugs)

• Unplug any sensors/connectors attached to the upper intake using a pick tool as needed.
• Disconnect intake/vacuum/EVAP hoses carefully using a flat trim tool for stubborn fittings.
• Remove the upper intake manifold bolts using a 10mm socket and 1/4" drive ratchet.
• Lift the upper intake manifold straight up and off.
• Cover the exposed intake ports with clean rags immediately.

Step 5: Remove ignition coils and spark plugs on the driver side

• Unplug coil connectors using a pick tool, then remove coil bolts with a 10mm socket.
• Remove the coils and blow out the plug wells using the compressed air blow gun.
• Remove and replace spark plugs using a 5/8" spark plug socket, 12" extension (3/8"), 3/8" universal joint, and 3/8" drive ratchet.
• Tighten spark plugs: Torque to 18 Nm (13 ft-lbs).

Step 6: Reinstall coils

• Apply a small amount of dielectric grease inside each coil boot (the rubber end that seals on the plug).
• Push each coil straight onto its plug until fully seated.
• Install coil bolts using a 10mm socket and tighten: Torque to 8 Nm (71 in-lbs).
• Reconnect coil electrical connectors until they click/lock.

Step 7: Reinstall the upper intake manifold

• Remove rags from intake ports.
• Install new intake manifold gaskets (do not reuse flattened ones).
• Set the manifold in place and hand-start all bolts.
• Tighten manifold bolts evenly: Torque to 10 Nm (89 in-lbs).
• Reconnect all hoses and electrical connectors you removed.

Step 8: Reinstall the intake tube and battery connection

• Reinstall the intake tube and tighten clamps using an 8mm socket.
• Reconnect the negative battery cable using a 10mm socket.
• Reinstall the engine cover by pressing it down onto the grommets.

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✅ After Repair

• Start the engine and let it idle for 1-2 minutes.
• Listen for hissing (a vacuum leak) around the intake manifold area.
• If you have a check-engine light after the repair, re-check every coil connector and intake hose connection first.
• Test drive gently, then recheck for any warning lights.

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💰 DIY vs Shop Cost

Shop Cost: $300-$650 (parts + labor)

DIY Cost: $60-$180 (parts only)

You Save: $240-$470 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?

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.