🔧 Ignition Coils - Replacement

Your Prius C uses four coil-on-plug ignition coils mounted directly on top of the spark plugs. Replacing them is straightforward once the engine cover and intake ducting are out of the way, and it can fix misfires, rough running, or a check engine light.

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

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⚠️ Safety & Precautions

• Work with the vehicle in READY off and the ignition fully turned off.
• Let the engine cool completely before starting.
• Disconnect the 12V battery negative terminal before unplugging ignition coils.
• Do not touch the orange hybrid cables. They are high-voltage components.
• Keep dirt out of the spark plug wells. Dirt can cause misfires.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• Ratchet
• 6-inch extension
• Flat trim tool
• Needle-nose pliers
• Torque wrench
• Gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 4
• Spark plug tube seals - Qty: 4 if damaged or oil-soaked

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Make sure the car is fully off.
• Disconnect the 12V battery negative terminal using a 10mm socket.
• Wait a few minutes after disconnecting before handling coil connectors.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover and intake duct

• Use your hands or a flat trim tool to lift off the plastic engine cover.
• Use a 10mm socket and ratchet to loosen the intake duct clamps if the duct blocks access.
• Remove any fresh air ducting that prevents access to the coil connectors.

Step 2: Disconnect the coil electrical connectors

• Use a small flat trim tool or your fingers to release each coil connector lock.
• Pull the connector straight back to unplug it.
• Do not pull on the wires.

Step 3: Remove the ignition coils

• Use a 10mm socket and ratchet to remove the coil hold-down bolts, if equipped.
• Twist each coil slightly, then pull it straight up out of the spark plug well.
• If a coil is stuck, use a gentle side-to-side motion. Do not pry hard.

Step 4: Install the new ignition coils

• Compare the new coils to the old ones to confirm they match.
• Push each new coil straight down until it seats fully on the spark plug.
• Reinstall the hold-down bolts and Torque to 8 Nm (71 in-lbs).

Step 5: Reconnect the connectors and reinstall removed parts

• Reconnect each coil electrical connector until it clicks.
• Reinstall any intake ducting removed earlier.
• Reinstall the engine cover.

Step 6: Reconnect the battery and start the vehicle

• Reconnect the 12V battery negative terminal using a 10mm socket.
• Start the car and let it idle.
• Check for a smooth idle and make sure the check engine light is off.

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✅ After Repair

• Test drive the vehicle and confirm the misfire is gone.
• If the check engine light remains on, clear codes with a scan tool.
• If oil was found in the plug wells, inspect the valve cover gasket and tube seals.

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💰 DIY vs Shop Cost

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

DIY Cost: $80-$240 (parts only)

You Save: $140-$280 by doing it yourself!

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