How to Replace Ignition Coils on a 2010 Subaru Outback (Misfire & Rough Idle Fix)
Step-by-step coil-on-plug replacement with tools, parts list, safety tips, and 7.5 Nm (66 in-lbs) torque spec for 2010, 2011, 2012
How to Replace Ignition Coils on a 2010 Subaru Outback (Misfire & Rough Idle Fix)
Step-by-step coil-on-plug replacement with tools, parts list, safety tips, and 7.5 Nm (66 in-lbs) torque spec for 2010, 2011, 2012
🔧 Outback - Ignition Coil Replacement
Your Outback uses one ignition coil per cylinder (coil-on-plug). Replacing a bad coil can fix misfires, rough idle, and blinking check-engine light, and it’s a good DIY job if you work carefully and don’t mix up connectors.
Difficulty Level: Beginner | Estimated Time: 0.5-1.5 hours
⚠️ Safety & Precautions
- ⚠️ Work on a cool engine; coils sit near hot exhaust parts.
- ⚠️ Disconnect the negative battery cable to prevent accidental shorts.
- ⚠️ Do not pull on wires; only pull on connectors.
- ⚠️ If the check-engine light is blinking, avoid hard driving until fixed (active misfire can damage the catalytic converter).
🔧 Required Tools
You'll need the following tools for this repair:
- 10mm socket
- 1/4" drive ratchet
- 6" extension (1/4" drive)
- Torque wrench (inch-pound or low-range Nm)
- Flat trim tool
- Needle-nose pliers
- Shop light
- Nitrile gloves
- Safety glasses
🔩 Required Parts
HowToo sells all the parts you need for this repair:
- Ignition coil - Qty: 1-4
- Dielectric grease (spark plug boot grease) - Qty: 1
📋 Before You Begin
- 🅿️ Park on level ground, set the parking brake, and open the hood.
- 🔋 Use a 10mm socket to disconnect the negative battery cable and tuck it aside so it can’t spring back.
- 🧠 If you’re replacing only one coil, consider labeling cylinders/connectors with tape to avoid mix-ups.
🔨 Step-by-Step Instructions
Follow these steps in order:
Step 1: Gain access to the coils
- Use a shop light to locate the four coils (one at each cylinder head port, near the valve cover).
- If anything blocks access on a side (intake duct/air box pieces), release clamps/clips using a flat trim tool and needle-nose pliers, then move the item aside without stretching hoses.
Step 2: Unplug the coil electrical connector
- Press the connector lock tab by hand; if it’s stubborn, gently help the tab with a flat trim tool.
- Pull the connector straight off the coil (do not pull on the wiring).
Step 3: Remove the coil retaining bolt
- Use a 10mm socket, 1/4" drive ratchet, and 6" extension (1/4" drive) to remove the single bolt holding the coil.
- Set the bolt somewhere safe so it doesn’t fall into the engine bay.
Step 4: Remove the ignition coil
- Twist the coil slightly by hand to break the seal, then pull it straight out.
- If it sticks, twist—don’t pry hard.
Step 5: Prep and install the new coil
- Apply a small dab of dielectric grease (spark plug boot grease) inside the new coil boot.
- Push the new coil straight onto the spark plug until it fully seats (you’ll feel it bottom out).
Step 6: Reinstall the retaining bolt and torque it
- Start the bolt by hand to avoid cross-threading, then snug it with the 10mm socket.
- Use a torque wrench (a tool that tightens bolts to a precise setting) to finish: Torque to 7.5 Nm (66 in-lbs).
Step 7: Reconnect the electrical connector
- Push the connector onto the coil until it clicks/locks in place.
- Gently tug to confirm it’s latched.
Step 8: Repeat for any other coils
- Replace coils one at a time so connectors never get mixed up.
- If you’re replacing multiple coils, keep the old ones in order in case you need to compare them.
Step 9: Reconnect the battery
- Use a 10mm socket to reconnect the negative battery cable and tighten it securely (snug, not crushed).
✅ After Repair
- 🔍 Start the engine and let it idle for 1-2 minutes; it should run smooth with no shaking.
- 🛣️ Take a short test drive and confirm there’s no hesitation under light acceleration.
- 🧾 If the check-engine light stays on, the code may need to be cleared (a parts-store scan tool can do this), or there may be another cause (spark plug, wiring, vacuum leak).
- 👃 Stop and recheck for any fuel smell, loose hoses, or anything left unplugged near the intake.
💰 DIY vs Shop Cost
Shop Cost: $250-$650 (parts + labor, depending on how many coils)
DIY Cost: $60-$400 (parts only, depending on how many coils)
You Save: $190-$250+ by doing it yourself!
Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.7-1.5 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.


















