🔧 Impreza - Ignition Coil Replacement

Your Impreza uses one ignition coil per cylinder to fire the spark plugs. If a coil is failing, you’ll often get a misfire, rough idle, flashing check engine light, or a misfire code (P0301–P0304). Replacing coils is straightforward, but access is tight on the sides of the engine.

Difficulty Level: Intermediate | Estimated Time: 1.0-2.0 hours

---

⚠️ Safety & Precautions

• ⚠️ Work on a cool engine to avoid burns.
• ⚠️ Disconnect the negative battery terminal before unplugging coils.
• ⚠️ Do not pull on wiring; release the connector lock first.
• ⚠️ If the check engine light was flashing, avoid driving until fixed.

---

🔧 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)
• Universal joint (1/4" drive)
• Torque wrench (inch-pound)
• Flat-blade screwdriver
• Trim clip remover
• Needle-nose pliers
• Flashlight
• Nitrile gloves
• Safety glasses

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 1-4
• Dielectric grease - Qty: 1

---

📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Open the hood and let the engine cool fully.
• Disconnect the battery negative terminal using a 10mm socket.
• Replace one coil at a time to avoid mix-ups.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Grip the cover and pull upward to release it from the rubber grommets.
• If any clips are used, release them with a trim clip remover.

Step 2: Create access to the coil you’re replacing

• Passenger side access: Loosen intake duct clamps with a flat-blade screwdriver, then remove the duct/resonator pieces as needed.
• Driver side access: Move any small brackets/hoses out of the way carefully (do not kink hoses). Use needle-nose pliers only if a spring clamp needs repositioning.
• Use a flashlight to locate the coil (it’s the small unit bolted to the side of the engine with an electrical connector).

Step 3: Unplug the ignition coil connector

• Press the connector lock tab and pull the connector straight off.
• If it’s stuck, gently help it with a flat-blade screwdriver on the connector body (not the wires).

Step 4: Remove the ignition coil retaining bolt

• Remove the bolt using a 10mm socket, 1/4" ratchet, and a 3" or 6" extension.
• If the angle is tight, use the universal joint (1/4" drive).

Step 5: Remove the ignition coil

• Twist the coil slightly by hand, then pull it straight out.
• If it fights you, wiggle—don’t pry hard.

Step 6: Prep and install the new ignition coil

• Apply a small smear of dielectric grease inside the new coil boot (the rubber part that seals on the spark plug).
• Push the coil straight onto the spark plug until it seats fully.
• Install the retaining bolt by hand first (prevents cross-threading).
• Tighten with a torque wrench (inch-pound): Torque to 6.4 Nm (57 in-lbs / 4.7 ft-lbs).

Step 7: Reconnect the coil connector

• Push the connector on until it clicks.
• Gently tug it to confirm it’s locked.

Step 8: Reassemble the intake/removed items

• Reinstall any intake ducting and tighten clamps with a flat-blade screwdriver.
• Reinstall the engine cover by aligning it and pushing down firmly.

Step 9: Reconnect the battery

• Reconnect the negative terminal using a 10mm socket.

---

✅ After Repair

• Start the engine and let it idle for 1-2 minutes. It should run smoothly.
• Test drive gently and verify no flashing check engine light.
• If the check engine light stays on, the code may need clearing after the repair.
• If you still have a misfire, the spark plug for that cylinder may be worn or oil-contaminated.

---

💰 DIY vs Shop Cost

Shop Cost: $180-$500 (parts + labor)

DIY Cost: $45-$320 (parts only)

You Save: $135-$180 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-2.0 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.