🔧 Ignition Coil - Replacement

Your Sienna uses one ignition coil per cylinder on the 3.5L V6. Replacing a bad coil is straightforward, but you need to work carefully around the engine cover and wiring connectors so you do not damage the boots or plugs.

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

---

⚠️ Safety & Precautions

• Let the engine cool completely before starting. Ignition coils and spark plugs can be very hot.
• Turn the ignition off and remove the key/fob from the vehicle.
• Disconnect the negative battery cable with a 10mm wrench if you want extra electrical safety. This is recommended.
• Do not pull on the wiring; release each coil connector lock before unplugging it.
• Keep dirt out of the spark plug tubes. Debris can fall into the cylinder head.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 1/4-inch ratchet
• 6-inch extension
• Trim panel tool
• Flat blade screwdriver
• Torque wrench
• Dielectric grease
• Safety glasses
• Nitrile gloves

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 1 per failed cylinder
• Engine cover grommet clips - Qty: As needed

---

📋 Before You Begin

• Park on level ground and set the parking brake.
• Let the engine cool down fully.
• If you are replacing one coil only, it is best to replace the failed one and inspect the spark plug in that cylinder.
• For the 3.5L V6, the front bank is easiest to access first. The rear bank sits closer to the firewall.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Use your hands to lift the plastic engine cover straight up.
• If it feels stuck, gently pry up with a trim panel tool at the retaining points.
• Pull straight up, not sideways.

Step 2: Access the coil you are replacing

• Locate the ignition coil on the cylinder you are servicing.
• On the 3.5L V6, each coil sits directly on top of a spark plug.
• Make sure the area is clean before unplugging anything.

Step 3: Disconnect the coil connector

• Use a flat blade screwdriver if needed to release the connector lock.
• Press the connector tab and pull the plug straight off the coil.
• Do not yank on the wires.

Step 4: Remove the ignition coil bolt

• Use a 10mm socket and 1/4-inch ratchet to remove the coil retaining bolt.
• Keep the bolt safe so it does not fall into the engine bay.

Step 5: Pull out the old coil

• Grip the coil body and pull it straight up out of the spark plug tube.
• If it is stuck, wiggle it gently while lifting.
• Inspect the coil boot for oil, cracks, or burning.

Step 6: Install the new coil

• Apply a very small amount of dielectric grease inside the coil boot.
• Slide the new coil straight down onto the spark plug until fully seated.
• Reinstall the coil retaining bolt and Torque to 7.8 Nm (69 in-lbs).

Step 7: Reconnect the connector and repeat if needed

• Push the electrical connector onto the coil until it clicks.
• If you are replacing more than one coil, repeat the same steps for each cylinder.

Step 8: Reinstall the engine cover

• Align the cover with its mounts and press it down until it seats fully.

---

✅ After Repair

• Start the engine and listen for smooth idle.
• Check the dashboard for the check engine light.
• If a misfire code was present, clear it with a scan tool and verify it does not return.
• If the engine still runs rough, the spark plug or wiring for that cylinder may also need inspection.

---

💰 DIY vs Shop Cost

Shop Cost: $220-$520 (parts + labor)

DIY Cost: $40-$180 (parts only)

You Save: $180-$340 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1-2 hours.

---

🎯 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.