🔧 Grand Cherokee - Ignition Coil Replacement

Replacing the ignition coils on your Grand Cherokee helps fix misfires, rough idle, poor acceleration, and check-engine-light codes related to spark. The 5.7L V8 uses one ignition coil per cylinder, mounted on top of the spark plugs under the engine cover.

Difficulty Level: Beginner | Estimated Time: 1-2 hours

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⚠️ Safety & Precautions

• ⚠️ Work only on a cold engine to avoid burns from the cylinder heads and exhaust manifolds.
• ⚠️ Disconnect the negative battery cable before unplugging ignition coils.
• ⚠️ Ignition coils create high voltage when operating, so never unplug or handle them with the engine running.
• ⚠️ Keep dirt out of the spark plug wells. Dirt can fall into the engine if the spark plugs are removed later.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 8mm socket
• 1/4-inch drive ratchet
• 3/8-inch drive ratchet
• 6-inch socket extension
• Small flathead screwdriver
• Torque wrench inch-pound range
• Compressed air blower
• Shop towels
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coils - Qty: 8 if replacing all, or Qty: 1 per failed cylinder
• Dielectric grease - Qty: 1 small tube

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📋 Before You Begin

• 🅿️ Park your Grand Cherokee on level ground, shift to Park, and set the parking brake.
• ❄️ Let the engine cool completely before starting.
• 🔋 Use a 10mm socket to disconnect the negative battery cable, then move the cable aside so it cannot touch the battery post.
• 🧠 If replacing only one coil, identify the failed cylinder first using a scan tool misfire code such as P0301-P0308.
• 📌 A cylinder is one engine hole where fuel burns; this V8 has 8 cylinders and 8 coils.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the Engine Cover

• Use both hands to lift the plastic engine cover straight upward.
• The cover is held by rubber grommets, which are soft push-in retainers.
• Set the cover aside where it will not get stepped on.
• Lift evenly to avoid cracking it.

Step 2: Locate the Ignition Coils

• Look along both sides of the intake manifold for the ignition coils.
• Each coil is a small black plastic unit with an electrical connector on top.
• There are 8 coils total, one for each cylinder.
• If replacing all coils, work on one coil at a time so nothing gets mixed up.

Step 3: Clean Around the Coil Area

• Put on safety glasses.
• Use a compressed air blower to blow dirt and grit away from the top of each ignition coil.
• Use shop towels to wipe around the coil mounting area.
• This keeps debris from falling into the spark plug well, which is the deep pocket where the spark plug sits.

Step 4: Unplug the Ignition Coil Connector

• Use your thumb to press the electrical connector release tab.
• If the tab is stuck, use a small flathead screwdriver to gently lift the lock while pulling the connector straight back.
• Do not pull on the wires.
• Old plastic breaks easily.

Step 5: Remove the Coil Mounting Bolt

• Use an 8mm socket, 1/4-inch drive ratchet, and 6-inch socket extension to remove the ignition coil mounting bolt.
• Place the bolt in a safe spot so it does not fall into the engine bay.
• If your replacement coil did not include a new bolt, reuse the original bolt.

Step 6: Remove the Old Ignition Coil

• Grip the coil body by hand and twist it gently left and right.
• Pull the coil straight upward off the spark plug.
• If it feels stuck, keep twisting gently while pulling upward.
• Do not pry hard against the plastic coil body.

Step 7: Prepare the New Ignition Coil

• Compare the new coil to the old coil to make sure the shape and connector match.
• Apply a small pea-sized amount of dielectric grease inside the rubber boot of the new coil.
• Dielectric grease is electrical-safe grease that helps prevent moisture and makes future removal easier.
• Do not pack the boot full of grease.

Step 8: Install the New Ignition Coil

• Push the new ignition coil straight down onto the spark plug.
• You should feel the rubber boot seat firmly over the spark plug.
• Align the mounting hole with the bolt hole in the valve cover.

Step 9: Tighten the Coil Mounting Bolt

• Start the bolt by hand first to avoid cross-threading.
• Use an 8mm socket, 1/4-inch drive ratchet, and 6-inch socket extension to snug the bolt.
• Use a torque wrench inch-pound range to tighten the bolt to Torque to 9 Nm (80 in-lbs).
• Do not overtighten. The valve cover threads can be damaged.

Step 10: Reconnect the Electrical Connector

• Push the electrical connector straight onto the ignition coil until it clicks.
• Lightly tug the connector by the plastic body to make sure it is locked in place.
• Repeat Steps 4-10 for each ignition coil you are replacing.

Step 11: Reinstall the Engine Cover

• Line up the engine cover with its rubber mounting grommets.
• Press down firmly by hand until the cover seats fully.
• Make sure no wiring is trapped under the cover.

Step 12: Reconnect the Battery

• Use a 10mm socket and 3/8-inch drive ratchet to reconnect the negative battery cable.
• Tighten the battery terminal snugly.
• Do not overtighten the clamp.

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✅ After Repair

• ✅ Start the engine and let it idle for 1-2 minutes.
• ✅ Listen for smooth idle and check that the engine does not shake.
• ✅ If a check engine light was on, clear the codes with a scan tool after the repair.
• ✅ Test drive gently for 10-15 minutes and confirm there is no hesitation or flashing check engine light.
• ✅ If the same cylinder misfire returns, the spark plug, injector, wiring, or compression may also need diagnosis.

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💰 DIY vs Shop Cost

Shop Cost: $450-$950 for all 8 coils, or $160-$300 for one coil

DIY Cost: $180-$520 for all 8 coils, or $35-$90 for one coil

You Save: $125-$430 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.8-1.5 hours.

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🎯 Ready to get started?

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