🔧 Civic - Spark Plug Replacement

Replacing spark plugs restores strong ignition, smooth idle, and good fuel economy. On your Civic, the plugs sit under the ignition coils on top of the engine, so access is straightforward with basic hand tools.

Difficulty Level: Beginner | Estimated Time: 1-2 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and thread damage.
• ⚠️ Keep dirt out of the spark plug holes—debris can damage the engine.
• ⚠️ If you disconnect the battery, use a 10mm wrench and remove the negative terminal first.
• ⚠️ Do not over-tighten spark plugs—stripped threads are a costly repair.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 10mm socket
• 3/8" ratchet
• 3/8" torque wrench (10-80 ft-lbs range)
• 6" 3/8" drive extension
• 16mm spark plug socket (5/8")
• Small flathead screwdriver
• Compressed air blow gun
• Feeler gauge set

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (OEM-equivalent) - Qty: 4
• Dielectric grease - Qty: 1

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📋 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).
• If you choose to disconnect the battery: use a 10mm wrench to remove the negative (-) cable and set it aside so it can’t spring back.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• If your Civic has a plastic engine cover, lift it off by hand. If it’s bolted, use a 10mm socket and 3/8" ratchet to remove the fasteners.

Step 2: Unplug and remove the ignition coils

• Ignition coil (also called a “coil pack”) is the part that sits on top of each spark plug and delivers high voltage to fire it.
• Press the connector tab and pull the electrical connector off each coil. If it’s stubborn, gently help the tab with a small flathead screwdriver.
• Use a 10mm socket and 3/8" ratchet to remove each coil hold-down bolt.
• Twist the coil slightly, then pull it straight up and out.
• Tip: Lay coils in order to keep them organized.

Step 3: Clean around the spark plug wells

• Use a compressed air blow gun to blow out dirt around each plug hole before removing the plug.
• This helps prevent debris from falling into the cylinder.

Step 4: Remove the old spark plugs

• Install the 16mm spark plug socket (5/8") onto a 6" 3/8" drive extension and 3/8" ratchet.
• Turn counterclockwise to loosen, then remove the plug the rest of the way.
• If a plug feels extremely tight, stop and work it gently back and forth to avoid damaging threads.

Step 5: Check the new plug gap (do not bend fine-wire tips)

• Use a feeler gauge set to confirm the gap matches the plug’s spec on the box.
• Most iridium plugs come pre-gapped—if it’s off, exchange the plug instead of forcing the electrode.
• Tip: Don’t use a wedge-style gapping tool.

Step 6: Install the new spark plugs by hand first

• Place a new plug into the 16mm spark plug socket (5/8") (it holds the plug so it won’t fall).
• Thread the plug in by hand using only the extension (no ratchet at first) to prevent cross-threading.
• Once it’s seated, attach the torque wrench and tighten to: Torque to 25 Nm (18 ft-lbs).
• Tip: If it doesn’t thread easily, back out and restart.

Step 7: Reinstall the ignition coils

• Put a small dab of dielectric grease inside each coil boot (the rubber tube). This helps prevent moisture and makes future removal easier.
• Push the coil straight down until fully seated.
• Install the coil hold-down bolt using a 10mm socket and torque wrench: Torque to 12 Nm (9 ft-lbs).
• Reconnect each electrical connector until it clicks.

Step 8: Reinstall the engine cover and reconnect the battery (if removed)

• Reinstall the engine cover (hand press or use a 10mm socket if bolted).
• If you disconnected the battery, reconnect the negative (-) terminal using a 10mm wrench and tighten snugly.

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✅ 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 that every coil connector is fully clicked in.
• Take a short test drive and confirm normal power and no warning lights.

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💰 DIY vs Shop Cost

Shop Cost: $220-$450 (parts + labor)

DIY Cost: $40-$120 (parts only)

You Save: $180-$330 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.

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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.