🔧 Focus - Ignition Coil Replacement

Your Focus uses individual coil-on-plug ignition coils mounted directly on top of the spark plugs. Replacing them is a beginner-friendly repair that can fix misfires, rough idle, poor acceleration, and check-engine-light codes related to ignition coil failure.

Difficulty Level: Beginner | Estimated Time: 30-60 minutes

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⚠️ Safety & Precautions

• ⚠️ Work only with the engine fully cool, because the cylinder head and ignition components can get very hot.
• ⚠️ Disconnect the negative battery cable before unplugging ignition coils to reduce the chance of electrical shorts.
• ⚠️ Do not pull on the wiring itself. Always press the connector tab and pull the connector body.
• ⚠️ Replace coils one at a time if possible so the connectors stay organized.

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🔧 Required Tools

You'll need the following tools for this repair:

• 8mm socket
• 10mm socket
• 1/4-inch drive ratchet
• 1/4-inch drive 6-inch extension
• Torque wrench inch-pound range
• Trim clip removal tool
• Flathead screwdriver small
• Needle-nose pliers
• Safety glasses
• Nitrile gloves

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 1-4
• Dielectric grease - Qty: 1 small tube

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📋 Before You Begin

• 🅿️ Park your Focus on level ground, shift to neutral, set the parking brake, and turn the key off.
• 🌡️ Let the engine cool for at least 30 minutes before touching ignition components.
• 🔋 Use a 10mm socket to loosen the negative battery terminal, then move the cable aside so it cannot spring back onto the battery post.
• 🧠 A coil-on-plug ignition coil is the small electrical unit that sits directly over each spark plug and sends high voltage to fire the plug.
• 🧴 Dielectric grease is a non-conductive silicone grease used inside the rubber coil boot to help prevent moisture intrusion and sticking.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the Engine Appearance Cover

• Use your hands to lift the plastic engine cover straight upward if equipped.
• If any clips resist, use a trim clip removal tool to gently lift the cover at the mounting points.
• Set the cover aside where it will not get stepped on.
• Lift evenly to avoid cracking plastic.

Step 2: Locate the Ignition Coils

• The ignition coils are lined up across the top of the engine, one coil per cylinder.
• Each coil has an electrical connector and a small retaining bolt.
• If replacing only one coil, match it to the cylinder or misfire code you diagnosed before starting.

Step 3: Unplug the Coil Electrical Connector

• Use your thumb to press the locking tab on the coil connector.
• If the tab is stiff, use a small flathead screwdriver to gently help depress the tab.
• Pull the connector straight back from the coil body.
• Use needle-nose pliers only on the connector body if extra grip is needed.
• Never pull on the wires.

Step 4: Remove the Coil Retaining Bolt

• Use an 8mm socket, 1/4-inch drive ratchet, and 6-inch extension to remove the ignition coil retaining bolt.
• Place the bolt in a small tray or pocket so it does not fall into the engine bay.

Step 5: Remove the Old Ignition Coil

• Grip the top of the coil by hand and twist it gently left and right.
• Pull the coil straight upward out of the spark plug well.
• If the rubber boot sticks, keep twisting gently while pulling upward.
• Inspect the old coil for oil, coolant, cracking, burning, or a torn rubber boot.
• If oil is inside the spark plug well, the valve cover gasket may also need repair before installing new coils.

Step 6: Prepare the New Ignition Coil

• Apply a very thin film of dielectric grease inside the end of the rubber boot using a gloved fingertip.
• Do not pack the boot with grease. Too much can prevent the boot from seating correctly.
• Compare the new coil to the old coil to make sure the connector and boot shape match.

Step 7: Install the New Ignition Coil

• Push the new coil straight down into the spark plug well by hand.
• You should feel the boot seat over the spark plug.
• Install the retaining bolt by hand first to avoid cross-threading.
• Use an 8mm socket, 1/4-inch drive ratchet, and torque wrench to tighten the coil retaining bolt to Torque to 6 Nm (53 in-lbs).
• Start bolts by hand first.

Step 8: Reconnect the Coil Connector

• Push the electrical connector onto the ignition coil until it clicks.
• Gently tug on the connector body by hand to confirm it is locked.

Step 9: Repeat for Remaining Coils

• If replacing more than one coil, repeat Steps 3 through 8 for each ignition coil.
• Replace one coil at a time to avoid mixing up connectors.
• If replacing all four, replace all four coils across the top of the engine.

Step 10: Reinstall the Engine Cover and Battery Cable

• Use your hands to press the engine cover back onto its mounting points if equipped.
• Use a 10mm socket and ratchet to reconnect the negative battery cable.
• Tighten the negative battery terminal snugly to Torque to 5 Nm (44 in-lbs) if using a torque wrench.

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✅ After Repair

• ✅ Start your Focus and let it idle for 1-2 minutes.
• ✅ Listen for a smooth idle with no shaking or stumble.
• ✅ If the check engine light was on, use a scan tool to clear stored misfire codes after confirming the engine runs smoothly.
• ✅ Test drive gently for 10-15 minutes and confirm normal acceleration.
• ✅ If the same misfire returns, check the spark plug, injector, compression, and wiring for that cylinder.

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💰 DIY vs Shop Cost

Shop Cost: $180-$550 (parts + labor)

DIY Cost: $35-$260 (parts only)

You Save: $145-$290 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.0 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.