🔧 Ignition Coils - Replacement

Your Prius uses coil-on-plug ignition coils mounted directly on top of the spark plugs. Replacing a faulty coil can fix a misfire, rough idle, flashing check engine light, or hard starting. On a hybrid, the engine can start unexpectedly, so the high-voltage system and 12V safety steps matter.

Difficulty Level: Beginner | Estimated Time: 0.5-1.0 hours

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⚠️ Safety & Precautions

• Disable the hybrid system before working. Remove the key/fob from the vehicle and keep it away from the car.
• Power down fully before touching ignition components. The engine may start automatically if the hybrid system is active.
• Let the engine cool if it has been running. Coil boots and valve cover areas can be hot.
• Disconnect the 12V battery negative terminal if you want the safest setup.
• Do not touch the orange high-voltage cables or hybrid components.

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🔧 Required Tools

You'll need the following tools for this repair:

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

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 1
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground and shift to Park.
• Press the Power button OFF and confirm the car is fully shut down.
• Remove the key/fob from the cabin.
• If disconnecting the battery, disconnect the 12V negative terminal first.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Open the engine cover area

• Open the hood and remove the plastic engine cover, if equipped.
• Lift it straight up by hand. If it feels stuck, gently work it free from the retaining grommets.
• Pull straight up, not sideways.

Step 2: Disconnect the ignition coil connector

• Find the coil you are replacing on top of the engine.
• Press the locking tab and unplug the electrical connector by hand.
• If the connector is tight, use a small trim panel tool carefully to help release the tab.

Step 3: Remove the ignition coil

• Use a 10mm socket and 1/4-inch ratchet with extension to remove the coil hold-down bolt.
• Pull the coil straight up out of the spark plug well.
• If it sticks, twist it slightly by hand and lift again.

Step 4: Install the new ignition coil

• Compare the old coil and new coil to confirm they match.
• Apply a small amount of dielectric grease inside the coil boot.
• Push the new coil straight down onto the spark plug until fully seated.
• Reinstall the coil bolt by hand first, then tighten with a 10mm socket.
• Torque to 9 Nm (80 in-lbs).

Step 5: Reconnect and reassemble

• Reconnect the electrical connector until it clicks.
• Reinstall the engine cover by pressing it down onto the retaining points.
• If you disconnected the 12V battery, reconnect the negative terminal last.

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✅ After Repair

• Start the vehicle and let it idle in READY mode.
• Check for a smooth idle and no warning lights.
• If the check engine light was on, clear codes with a scan tool and confirm the misfire is gone.
• If the engine still shakes, the spark plug or injector may also need diagnosis.

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💰 DIY vs Shop Cost

Shop Cost: $180-$350 (parts + labor)

DIY Cost: $40-$140 (parts only)

You Save: $140-$210 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.0 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.