🔧 Fusion - Spark Plug Replacement

On your Fusion, the spark plugs fire the gasoline engine. Worn plugs can cause rough running, poor fuel economy, and misfires. This job is straightforward because the plugs sit under the ignition coils on top of the engine.

Difficulty Level: Intermediate | Estimated Time: 1.0-2.0 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and damaged threads.
• ⚠️ Turn the car completely OFF and keep the key fob at least 15 feet away so the hybrid system can’t wake up unexpectedly.
• ⚠️ Do not touch or probe any orange high-voltage cables or connectors.
• ⚠️ Battery disconnect is not required, but if you’re nervous, disconnect the 12V negative terminal to prevent accidental starting.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 8mm socket
• 3/8" drive ratchet
• 3/8" drive extension set (3" and 6")
• 5/8" spark plug socket
• Torque wrench (3/8" drive)
• Small flat trim tool
• Compressed air blower
• Dielectric grease
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (iridium, OEM-equivalent) - Qty: 4
• Ignition coil boots (optional, if torn/oil-soaked) - Qty: 4

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📋 Before You Begin

• 🅿️ Park on level ground and set the parking brake.
• 🧊 Let the engine cool completely (at least 1 hour after driving).
• 🔑 Turn ignition OFF and keep the key fob away from the car.
• 🧤 Put on nitrile gloves and safety glasses.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Grab the cover with both hands and pull upward to release the rubber grommets.
• If any corner feels stuck, use a small flat trim tool to gently help lift—don’t pry hard.

Step 2: Disconnect the ignition coil connectors

• Locate the 4 ignition coils on top of the engine (one per cylinder).
• Press the connector lock tab and pull the connector straight off.
• If the tab is stubborn, use the small flat trim tool to gently lift the lock. Don’t pull on the wires.

Step 3: Remove the ignition coils

• Remove each coil hold-down bolt using an 8mm socket with a 3/8" drive ratchet.
• Twist the coil slightly, then pull straight up to remove it.
• Set coils aside in order (so they go back in the same cylinder).

Step 4: Clean out the spark plug wells

• Blow compressed air down each spark plug hole using the compressed air blower.
• This prevents dirt from falling into the cylinder when the plug comes out.

Step 5: Remove the old spark plugs

• Use a 5/8" spark plug socket with a 3/8" drive extension and 3/8" drive ratchet to loosen and remove each plug.
• Turn slowly—if a plug feels like it’s binding, tighten slightly, then loosen again.

Step 6: Install the new spark plugs

• Confirm the new plugs match the old ones (same length and tip style).
• Do not use anti-seize on modern plated plugs.
• Start each plug by hand using the 5/8" spark plug socket and 3/8" drive extension only (no ratchet at first).
• Once hand-threaded, tighten with a torque wrench (3/8" drive): Torque to 15 Nm (11 ft-lbs).

Step 7: Reinstall the ignition coils

• Put a tiny smear of dielectric grease inside each coil boot (this helps prevent moisture and makes future removal easier). (Dielectric grease = non-conductive grease for electrical boots.)
• Push each coil straight down until fully seated on the plug.
• Install the coil bolts using an 8mm socket, then snug with a torque wrench (3/8" drive): Torque to 8 Nm (71 in-lbs).

Step 8: Reconnect everything and reinstall the cover

• Plug in each coil connector until it clicks.
• Reinstall the engine cover by lining up the grommets and pressing down firmly.

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✅ After Repair

• ✅ Start the car and let it idle for 1–2 minutes. It should run smooth with no shaking.
• ✅ If you have a check engine light or misfire, re-check that every coil connector is fully clicked in.
• ✅ Take a short test drive and confirm normal power and no warning lights.

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💰 DIY vs Shop Cost

Shop Cost: $250-$450 (parts + labor)

DIY Cost: $40-$120 (parts only)

You Save: $210-$330 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.5 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.