🔧 4Runner - Ignition Coil Replacement

Your 4Runner uses coil-on-plug ignition coils (one coil per cylinder). Replacing a bad coil can fix misfires, rough idle, and flashing check-engine light. The job is mostly access and careful connector handling.

Difficulty Level: Beginner | Estimated Time: 0.5-1.5 hours (one coil); 1-2.5 hours (all six)

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⚠️ Safety & Precautions

• ⚠️ Let the engine cool fully; coils sit on a hot cylinder head.
• ⚠️ Disconnect the negative battery cable to prevent accidental shorting.
• ⚠️ Don’t pull on wiring; press the connector lock and pull the plug body.
• ⚠️ If the check-engine light is flashing, avoid driving until repaired (active misfire can damage the catalytic converter).

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 1/4" drive ratchet
• 3" extension (1/4" drive)
• 6" extension (1/4" drive)
• Torque wrench (inch-pound or small Nm range)
• Flat trim tool
• Needle-nose pliers
• Shop light
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 1 (or Qty: 6 to replace all)
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Open the hood and let the engine cool.
• Use a 10mm socket to remove the negative battery terminal and isolate it so it can’t spring back. Prevents accidental shorts.
• If you’re chasing a misfire code, note which cylinder is flagged (example: P0303 = cylinder 3). Saves time.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Use a 10mm socket with a 1/4" drive ratchet to remove the cover fasteners.
• Lift the cover straight up and set it aside.

Step 2: Make room to reach the coil (as needed)

• For tight spots, use a flat trim tool to release any plastic clips holding wiring looms near the coil area.
• If a hose clamp or clip blocks access, use needle-nose pliers to open the clamp and slide the hose slightly aside (don’t remove more than necessary).
• Take a quick photo before moving anything.

Step 3: Unplug the ignition coil electrical connector

• Press the connector lock tab (the “click” tab) with your finger or a flat trim tool.
• Pull the connector straight off the coil. Do not pull on the wires.

Step 4: Remove the coil hold-down bolt

• Use a 10mm socket, 3" extension, and 1/4" drive ratchet to remove the coil bolt.
• Set the bolt somewhere safe so it can’t fall into the engine bay.

Step 5: Remove the ignition coil

• Grip the coil body and twist gently left-right to break the seal.
• Pull the coil straight upward to remove it from the spark plug tube.
• If it feels stuck, keep twisting gently—don’t pry hard against plastic parts.

Step 6: Prep and install the new coil

• Put a small dab of dielectric grease inside the new coil boot (the rubber sleeve that touches the spark plug). Dielectric grease is a non-conductive grease that helps prevent moisture and makes future removal easier.
• Push the coil straight down until it fully seats.

Step 7: Reinstall the coil bolt and torque it

• Start the bolt by hand to avoid cross-threading.
• Use a torque wrench with a 10mm socket to tighten the bolt: Torque to 9 Nm (80 in-lbf).

Step 8: Reconnect the coil connector

• Push the connector on until it clicks/locks.
• Re-clip any wiring looms you moved using the flat trim tool as needed.

Step 9: Reinstall engine cover and reconnect battery

• Reinstall the engine cover using the 10mm socket and 1/4" drive ratchet.
• Reconnect the negative battery terminal using the 10mm socket.

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✅ After Repair

• Start the engine and let it idle for 1-2 minutes; it should run smooth with no shaking.
• If you had a check-engine light, use a scan tool to clear codes and confirm the misfire does not return.
• Test drive 10-15 minutes, then recheck for warning lights.
• If the same cylinder still misfires, the spark plug or fuel injector may be the cause.

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💰 DIY vs Shop Cost

Shop Cost: $220-$650 (parts + labor, depends on how many coils)

DIY Cost: $45-$420 (parts only, depends on how many coils)

You Save: $175-$230+ by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.7-2.0 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.