🔧 Terrain - Ignition Coil Replacement

The ignition coils sit on top of the spark plugs and create the high voltage needed to fire the engine. Replacing a weak or failed coil can fix misfires, rough idle, flashing check-engine light, and poor acceleration.

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

---

⚠️ Safety & Precautions

• ⚠️ Work on a cool engine to avoid burns and to prevent damaging plastic connectors.
• ⚠️ Disconnect the negative battery cable to reduce the chance of an accidental short or surprise engine crank.
• ⚠️ Never pull on wiring; always release the connector lock and pull on the connector body.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 3/8" ratchet
• 3/8" extension set
• Torque wrench (5-30 ft-lbs range)
• Small flathead screwdriver
• Trim clip remover
• Nylon parts brush
• Shop towels
• Nitrile gloves
• Safety glasses
• OBD2 scan tool (specialty)

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 1 (or Qty: 4 if replacing all)
• Ignition coil boot - Qty: 1 (optional, if torn/oil-soaked)
• Dielectric grease - Qty: 1 (small packet)

---

📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Open the hood and let the engine cool fully.
• Use a 10mm socket to disconnect the negative battery cable and move it aside so it can’t spring back.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Lift straight up on the cover to release the rubber grommets, or remove any retainers using a trim clip remover.
• Set the cover aside where it won’t get stepped on.

Step 2: Locate the ignition coils

• The coils sit on top of the valve cover, directly above each spark plug.
• Each coil has an electrical connector and a small retaining bolt.

Step 3: Unplug the coil electrical connector

• Use a small flathead screwdriver only if needed to gently lift the connector lock (do not pry hard).
• Pull the connector straight off by hand. Wiggle the connector, don’t yank wires.

Step 4: Remove the coil retaining bolt

• Use a 10mm socket with a 3/8" ratchet and a 3/8" extension to remove the bolt.
• Place the bolt somewhere safe (a small tray helps).

Step 5: Remove the ignition coil

• Grip the coil body and pull straight upward while gently twisting.
• If it feels stuck, keep twisting and pulling upward—avoid using metal tools against the valve cover.

Step 6: Inspect for oil or contamination

• Check the coil boot (rubber sleeve) for cracks, swelling, or heavy carbon tracking (black lightning-like lines).
• If you see oil down in the spark plug well, wipe what you can with shop towels. Oil suggests a sealing issue that should be addressed.
• Lightly clean the area around the spark plug well using a nylon parts brush and shop towels.

Step 7: Prep the new coil

• Apply a small pea-sized amount of dielectric grease inside the tip of the coil boot (dielectric grease is a non-conductive grease that helps seal out moisture and prevents the boot from sticking).
• Do not smear grease on the electrical connector pins.

Step 8: Install the new coil

• Push the coil straight down onto the spark plug until you feel it seat firmly.
• Reinstall the retaining bolt by hand first (to avoid cross-threading), then snug with a 10mm socket.
• Finish with a torque wrench: Torque to 10 Nm (89 in-lbs).

Step 9: Reconnect the electrical connector

• Push the connector on until it clicks/locks in place.
• Give it a gentle tug to confirm it’s fully seated.

Step 10: Reassemble

• Reinstall the engine cover by pressing it onto the grommets, or reinstall retainers using a trim clip remover.
• Reconnect the negative battery cable using a 10mm socket and snug it securely.

---

✅ After Repair

• Start the engine and let it idle for 1-2 minutes. It should idle smoothly without shaking.
• If the check-engine light was on, use an OBD2 scan tool (a plug-in code reader) to clear codes and confirm no misfire returns.
• Take a short test drive and recheck for warning lights and abnormal hesitation.

---

💰 DIY vs Shop Cost

Shop Cost: $180-$450 (parts + labor)

DIY Cost: $40-$320 (parts only, depending on replacing 1 coil vs all 4)

You Save: $140-$130 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.7-1.2 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.