🔧 Forester - Ignition Coil Replacement

Your Forester uses one ignition coil per cylinder. Replacing a weak coil can fix misfires, rough idle, flashing check-engine light, and loss of power.

Difficulty Level: Beginner | Estimated Time: 0.5-1.5 hours

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⚠️ Safety & Precautions

• ⚠️ Let the engine cool completely; coils sit on hot engine parts.
• ⚠️ Turn ignition OFF and keep the key/fob away from the vehicle.
• ⚠️ If disconnecting the battery, remove the negative terminal first to reduce short risk.
• ⚠️ Don’t pull on wiring; release connector locks to avoid damage.

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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)
• Torque wrench (inch-pound or low-range ft-lb)
• Flat trim tool
• Needle-nose pliers
• Flashlight
• OBD-II scan tool (optional)
• 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: 4 to replace all)
• Dielectric grease - Qty: 1

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📋 Before You Begin

• 🧭 Park on level ground, shift to Park, and set the parking brake.
• 🔌 If you’re replacing only one coil: which cylinder is misfiring (ex: P0302)?
• 🧠 Dielectric grease is a non-conductive silicone grease that helps prevent moisture/corrosion in the rubber boot.
• 🔎 Cylinder numbering on your Forester: passenger side is cylinders 1 (front) and 3 (rear); driver side is 2 (front) and 4 (rear).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Use your hands to pull the engine cover straight upward to release the rubber grommets.
• If any clips feel stuck, use a flat trim tool to gently pry upward.

Step 2: Locate the coil you’re replacing

• Use a flashlight to find the coil sitting directly on top of the spark plug hole (one coil per cylinder).
• Do one coil at a time.

Step 3: Disconnect the electrical connector

• Press the connector lock tab and pull the connector straight back.
• If the tab is tight, gently help it with a flat trim tool (don’t break the lock).

Step 4: Remove the coil hold-down bolt

• Use a 10mm socket, 1/4" drive ratchet, and 3" extension (1/4" drive) to remove the coil mounting bolt.
• Set the bolt aside where it won’t get lost.

Step 5: Remove the ignition coil

• Grip the coil body and twist it slightly left-right to free the rubber boot seal, then pull it straight out.
• If it’s stubborn, use needle-nose pliers only to assist your grip on the coil body (do not crush it).

Step 6: Prep and install the new coil

• Apply a very small smear of dielectric grease inside the new coil boot (a pea-sized amount is plenty).
• Align the coil with the spark plug tube and push straight down until it fully seats.

Step 7: Reinstall the hold-down bolt and torque it

• Start the bolt by hand first to avoid cross-threading.
• Use a 10mm socket and torque wrench (inch-pound or low-range ft-lb) to tighten: Torque to 6.4 Nm (4.7 ft-lbs).

Step 8: Reconnect the electrical connector

• Push the connector on until it clicks/locks.
• Gently tug to confirm it’s latched.

Step 9: Reinstall the engine cover

• Line up the cover with the mounting points and push down firmly by hand until it snaps into place.

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✅ After Repair

• 🔁 Start the engine and let it idle for 1-2 minutes. It should be smooth.
• 🔎 If the check engine light was on, use an OBD-II scan tool to clear codes and confirm the misfire does not return. (An OBD-II scan tool reads/clears engine codes.)
• 🧪 Test drive 10-15 minutes and recheck for warning lights.
• 🛑 If you still have a misfire, the spark plug or injector for that cylinder may be the cause.

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💰 DIY vs Shop Cost

Shop Cost: $220-$480 (parts + labor, 1-2 coils)

DIY Cost: $60-$320 (parts only, 1-4 coils)

You Save: $160-$160+ 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.