🔧 Flex - Ignition Coil Replacement

Your Flex uses coil-on-plug ignition coils (one coil per cylinder). Replacing a bad coil fixes misfires, rough idle, flashing check-engine light, and loss of power.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.5 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a cool engine; the rear bank sits near hot components.
• ⚠️ Disconnect the negative battery cable to prevent accidental shorts.
• ⚠️ Do not pry on plastic connectors; use the lock tabs.
• ⚠️ Keep bolts and dirt out of the intake ports; cover openings with clean rags.

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🔧 Required Tools

You'll need the following tools for this repair:

• 7mm socket
• 8mm socket
• 10mm socket
• 1/4" drive ratchet
• 3/8" drive ratchet
• 3" extension
• 6" extension
• Torque wrench (inch-pound)
• Torque wrench (ft-lb)
• Flat trim tool
• Needle-nose pliers
• Hose clamp pliers
• Shop flashlight
• Clean shop rags
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Replace as needed (recommended set of 6) - Qty: 1-6
• Upper intake manifold gasket set - Qty: 1
• Throttle body gasket - 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.
• Let the engine cool completely.
• Disconnect the negative battery cable using a 10mm socket and move it aside.
• Tip: Take photos before unplugging connectors.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine appearance cover

• Pull up firmly to release the cover from its rubber grommets.

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

• Loosen the clamps using a 7mm socket.
• Disconnect any small vacuum/breather hoses using needle-nose pliers as needed.
• Lift the intake tube out and set it aside.

Step 3: Replace the front bank ignition coils (easy access)

• On the front bank, unplug each coil electrical connector by pressing the lock tab and pulling straight back.
• Remove each coil hold-down bolt using a 7mm socket.
• Twist the coil boot slightly, then pull the coil straight up and out.
• Apply a very thin smear of dielectric grease inside the new coil boot.
• Install the new coil fully onto the spark plug, reinstall the bolt, and Torque to 7 Nm (62 in-lb) using an inch-pound torque wrench.
• Reconnect the electrical connector until it clicks.
• Tip: A gentle twist helps the boot seat.

Step 4: Remove the throttle body (to access the upper intake manifold)

• Unplug the throttle body electrical connector.
• Remove the throttle body bolts using an 8mm socket.
• Remove the throttle body and the old gasket.
• Cover the opening with a clean rag.

Step 5: Remove the upper intake manifold (rear bank access)

• Disconnect the PCV/vacuum hoses and any electrical connectors attached to the upper intake using a flat trim tool to help release clips.
• Remove the upper intake manifold bolts using an 8mm socket with a 6" extension.
• Lift the upper intake manifold off carefully.
• Remove the old upper intake gaskets and keep debris out of the ports (use clean shop rags to cover the intake openings).

Step 6: Replace the rear bank ignition coils

• Unplug the rear bank coil electrical connectors.
• Remove the coil hold-down bolts using a 7mm socket.
• Remove and replace coils one at a time so nothing gets mixed up.
• Reinstall coil bolts and Torque to 7 Nm (62 in-lb) using an inch-pound torque wrench.
• Reconnect all coil connectors until they click.

Step 7: Reinstall the upper intake manifold with new gaskets

• Install new upper intake manifold gaskets onto the manifold.
• Remove the rags from the intake ports.
• Set the upper intake manifold in place.
• Install bolts finger-tight, then tighten evenly in a crisscross pattern using an 8mm socket.
• Torque to 10 Nm (89 in-lb) using an inch-pound torque wrench.

Step 8: Reinstall the throttle body with a new gasket

• Install the new throttle body gasket.
• Reinstall the throttle body and bolts using an 8mm socket.
• Torque to 10 Nm (89 in-lb) using an inch-pound torque wrench.
• Reconnect the throttle body electrical connector.

Step 9: Reinstall the air intake tube and engine cover

• Reinstall the intake tube and tighten clamps using a 7mm socket.
• Reconnect any breather/vacuum lines.
• Press the engine cover back onto its grommets.

Step 10: Reconnect the battery

• Reconnect the negative battery cable using a 10mm socket.

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✅ After Repair

• Start the engine and let it idle for 2–3 minutes. Expect a slightly rough idle for a few seconds while the throttle/idle strategy settles.
• Check for vacuum leaks: listen for hissing and confirm the intake tube and all hoses are fully seated.
• If you had a check-engine light, clear codes with a scan tool after confirming the misfire is gone.
• Test drive 10–15 minutes and recheck for warning lights.

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💰 DIY vs Shop Cost

Shop Cost: $350-$900 (parts + labor)

DIY Cost: $120-$480 (parts only)

You Save: $230-$420 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.