🔧 Yukon - Spark Plug Replacement

On your Yukon’s 6.2L V8, the spark plugs sit under the ignition coils (one coil per cylinder). Replacing them restores smooth idle, power, and fuel economy, and helps prevent misfires under load.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.0 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and stripped threads.
• ⚠️ Disconnect the negative battery cable if you’re likely to bump the starter/positive cable while working.
• ⚠️ Do not use anti-seize on modern nickel-plated spark plugs unless the plug maker explicitly says to; it can cause over-tightening.
• ⚠️ Blow dirt out of each plug well before removing the plug so debris doesn’t fall into the cylinder.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Ratchet (3/8")
• Torque wrench (3/8", ft-lb capable)
• 10mm socket
• 5/8" spark plug socket
• 3/8" drive extension set (3", 6")
• 3/8" drive swivel/universal joint
• Small flat screwdriver
• Trim clip tool
• Compressed air blow gun
• Feeler gauge set (inch/mm)
• Dielectric grease
• Magnetic pickup tool
• Flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (OEM-equivalent for 6.2L) - Qty: 8
• Ignition coil boots (optional, if torn/oil-soaked) - Qty: 8
• Ignition coil(s) (optional, if any are weak) - Qty: 1-8

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Let the engine cool completely (at least 1 hour after driving).
• If disconnecting the battery, use a 10mm socket to remove the negative cable and keep it from touching the terminal.
• Take a quick photo of each side before unplugging.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Lift up on the plastic engine cover to release it from its rubber grommets (use a trim clip tool only if needed).
• Set the cover aside so you can see the ignition coils along both valve covers.

Step 2: Start on one cylinder at a time

• Work one plug at a time so nothing gets mixed up.
• Each cylinder has an ignition coil on top of the spark plug. The coil makes the spark (no separate plug wires on this engine).

Step 3: Unplug the ignition coil electrical connector

• Use a small flat screwdriver to gently lift the connector lock (if equipped), then press the tab and pull the connector straight off.
• Pull on the connector body, not the wires.

Step 4: Remove the ignition coil

• Use a 10mm socket and 3/8" ratchet to remove the coil hold-down bolt.
• Twist the coil slightly, then pull it straight up to remove it from the spark plug well.
• Reinstall later with Torque to 10 Nm (89 in-lbs).

Step 5: Blow out the spark plug well

• Use a compressed air blow gun to blow dirt/debris out of the well.
• This prevents grit from falling into the cylinder when the plug comes out.

Step 6: Remove the old spark plug

• Install a 5/8" spark plug socket with a 3/8" extension (add a swivel/universal joint if needed for angle).
• Turn counterclockwise to remove the plug, then lift it out.
• If it feels extremely tight, stop and tighten slightly, then loosen again in small moves to avoid thread damage.

Step 7: Check and prep the new spark plug

• Check the gap using a feeler gauge set. Typical gap for this 6.2L is around 0.040 in (1.0 mm). If your new plugs include a spec label, follow that.
• Do not force the center electrode to adjust gap; only adjust if the plug manufacturer allows it.
• Put a small amount of dielectric grease inside the coil boot (this helps prevent moisture and makes future removal easier).

Step 8: Install the new spark plug (by hand first)

• Place the new plug into the 5/8" spark plug socket and guide it into the well.
• Thread it in by hand using only the extension (no ratchet) until it’s fully seated. This helps prevent cross-threading (damaging the threads in the cylinder head).
• Use a torque wrench to tighten: Torque to 18 Nm (13 ft-lbs).

Step 9: Reinstall the ignition coil

• Push the coil straight down onto the plug until fully seated.
• Install the hold-down bolt using a 10mm socket, then Torque to 10 Nm (89 in-lbs).
• Reconnect the electrical connector until it clicks/locks.

Step 10: Repeat for the remaining 7 spark plugs

• Repeat Steps 3–9 for each cylinder.
• Use a flashlight and magnetic pickup tool if you drop a bolt near the engine.

Step 11: Reinstall the engine cover and reconnect battery (if disconnected)

• Press the engine cover down into its grommets until it snaps in place.
• If you disconnected the battery, reconnect the negative cable using a 10mm socket and tighten securely.

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✅ After Repair

• Start the engine and let it idle for 1–2 minutes. It should be smooth with no shaking.
• Test drive and verify no hesitation under acceleration.
• If the check engine light is on or it runs rough, re-check that every coil connector is fully clicked in.
• If you have a scan tool, check for misfire codes (P0300–P0308) and clear any stored codes after the repair.

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💰 DIY vs Shop Cost

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

DIY Cost: $80-$180 (parts only)

You Save: $270-$470 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-3.0 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.