🔧 Terrain - Spark Plug Replacement

On your Terrain, the spark plugs sit under the ignition coils on top of the engine. Replacing them restores proper ignition, helps prevent misfires, and can improve idle and fuel economy when plugs are worn.

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

---

⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and thread damage in the aluminum cylinder head.
• ⚠️ Keep dirt out of the spark plug holes; debris can fall into the cylinder.
• ⚠️ Do not use anti-seize on spark plug threads unless the plug maker specifically says to; most modern plugs are nickel-plated and anti-seize can cause over-tightening.
• ⚠️ Battery disconnect is not required, but keep the ignition OFF and the key/fob away from the vehicle while unplugging coils.

---

🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 1/4" drive ratchet
• 3/8" drive ratchet
• 10mm socket
• 6" socket extension
• 12" socket extension
• 5/8" (16mm) spark plug socket
• Torque wrench (inch-pound or Nm capable)
• Small flat trim tool
• Compressed air blow gun
• Feeler gauge set
• Flashlight

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (iridium, correct for 1.5L turbo) - Qty: 4
• Dielectric grease - Qty: 1

---

📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Let the engine cool completely (at least 1 hour after driving).
• Open the hood and remove any loose items from the engine bay.
• Take a photo before unplugging anything.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Grip the cover firmly and pull upward to release the rubber grommets (no tools on most covers).
• Use a flashlight to confirm you can see the ignition coils on top of the engine.

Step 2: Unplug the first ignition coil connector

• Use a small flat trim tool to gently lift the connector lock (if present), then press the tab and pull the connector straight off.
• Do one coil at a time to avoid mix-ups.

Step 3: Remove the ignition coil bolt

• Use a 10mm socket with a 1/4" drive ratchet and a 6" socket extension to remove the coil hold-down bolt.
• Set the bolt aside where it won’t get lost.

Step 4: Remove the ignition coil

• Twist the coil boot slightly, then pull straight up to remove the coil.
• If it’s stuck, pull steadily—don’t pry on plastic.
• Apply a very small amount of dielectric grease inside the end of the coil boot only (this helps prevent sticking and keeps moisture out).

Step 5: Clean the spark plug well

• Use compressed air blow gun to blow out dust and grit from around the spark plug.
• Do not skip this—this is what keeps dirt from falling into the cylinder.

Step 6: Remove the spark plug

• Use a 5/8" (16mm) spark plug socket with a 3/8" drive ratchet and a 12" socket extension to loosen and remove the plug.
• Turn slowly at first; if it feels gritty, stop and blow out the well again with compressed air blow gun.

Step 7: Check the new spark plug gap

• Use a feeler gauge set to verify the gap matches the specification for your Terrain’s 1.5L turbo.
• Many iridium plugs are “pre-gapped”—avoid bending the fine center electrode. If the gap is off, exchange the plug rather than forcing it.

Step 8: Install the new spark plug

• Start the plug by hand using the 5/8" (16mm) spark plug socket and 12" socket extension only (no ratchet at first) to prevent cross-threading.
• Once it’s fully hand-threaded, tighten using a torque wrench (inch-pound or Nm capable).
• Torque to the spark plug manufacturer/OEM specification for your Terrain (use the spec provided with the plug or service information).

Step 9: Reinstall the ignition coil

• Push the coil straight down until it fully seats on the spark plug.
• Install the coil bolt using a 10mm socket and 1/4" drive ratchet, then finish with a torque wrench (inch-pound or Nm capable).
• Torque to the OEM specification for your Terrain (coil bolt torque varies by application).
• Reconnect the coil connector until it clicks; re-engage the lock if equipped.

Step 10: Repeat for the remaining cylinders

• Repeat Steps 2–9 for the remaining 3 spark plugs.
• Use a flashlight to confirm every connector is fully seated.

Step 11: Reinstall the engine cover

• Align the cover grommets and press down firmly until it seats.

---

✅ After Repair

• Start the engine and let it idle for 30–60 seconds; it should run smooth with no shaking.
• If the check engine light comes on or it runs rough, shut it off and re-check coil connectors and coil seating.
• Test drive 10–15 minutes and confirm no hesitation under light acceleration.

---

💰 DIY vs Shop Cost

Shop Cost: $250-$450 (parts + labor)

DIY Cost: $60-$140 (parts only)

You Save: $110-$390 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.5 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.