🔧 Civic - Spark Plug Replacement

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

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

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and to prevent damaging the aluminum cylinder head threads.
• ⚠️ Keep dirt out of the spark plug holes; debris can fall into the cylinder and cause damage.
• ⚠️ If you disconnect the battery, use a 10mm wrench and remove the negative terminal first.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 10mm socket
• 3/8" drive ratchet
• 3/8" drive extension set (3" and 6")
• 5/8" (16mm) spark plug socket
• Torque wrench (3/8" drive, 10-30 ft-lbs range)
• Small flathead screwdriver
• Compressed air blow gun
• Shop towels

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (OEM-type) - Replace all four - Qty: 4
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, put the transmission in neutral, and set the parking brake.
• Let the engine cool completely (at least 1 hour).
• Have compressed air ready to blow out each spark plug well before removing the plug.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Open access to the ignition coils

• Open the hood and locate the four ignition coils on top of the engine (one per cylinder).
• If any intake ducting is in your way, loosen its clamps using a 10mm socket and move it aside.

Step 2: Unplug the first ignition coil connector

• Work one cylinder at a time to avoid mixing anything up.
• Press the connector lock tab and unplug the coil; use a small flathead screwdriver gently if the tab is stubborn.
• Don’t pull on the wires.

Step 3: Remove the ignition coil

• Remove the coil hold-down bolt using a 10mm socket and 3/8" drive ratchet.
• Twist the coil slightly and pull it straight up to remove it from the spark plug well.
• On reassembly: Torque the ignition coil bolt to 12 N·m (9 ft-lbs).

Step 4: Blow out the spark plug well

• Use compressed air blow gun to blow dirt/loose debris out of the spark plug tube before loosening the plug.
• Wipe around the opening with shop towels.

Step 5: Remove the old spark plug

• Install the 5/8" (16mm) spark plug socket on a 3/8" drive extension and ratchet.
• Turn counterclockwise to loosen, then spin it out until it lifts out with the socket.
• If it feels extremely tight, stop and re-check that the engine is fully cool.

Step 6: Install the new spark plug (by hand first)

• Put the new plug into the 5/8" (16mm) spark plug socket.
• Lower it into the hole with the extension only (no ratchet) and thread it by hand clockwise several turns.
• This prevents cross-threading (damaging the threads in the aluminum head).
• Do not apply anti-seize unless the plug maker specifically requires it.

Step 7: Torque the spark plug

• Set your torque wrench and tighten the plug.
• Torque to 18 N·m (13 ft-lbs).

Step 8: Reinstall the ignition coil

• Apply a tiny dab of dielectric grease inside the rubber boot (this helps prevent moisture and makes future removal easier).
• Push the coil straight down until it seats fully on the plug.
• Install the hold-down bolt using a 10mm socket, then finish with a torque wrench.
• Torque the ignition coil bolt to 12 N·m (9 ft-lbs).
• Reconnect the electrical connector until it clicks.

Step 9: Repeat for the other three cylinders

• Repeat Steps 2 through 8 for the remaining coils/plugs.
• One cylinder at a time prevents mistakes.

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✅ After Repair

• Start the engine and let it idle for 30-60 seconds; it should run smooth with no flashing check-engine light.
• Listen for a ticking/air leak sound (can indicate a plug not fully seated).
• Take a short test drive and confirm normal power and no misfire.

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💰 DIY vs Shop Cost

Shop Cost: $200-$350 (parts + labor)

DIY Cost: $40-$90 (parts only)

You Save: $110-$310 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.8-1.2 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.