🔧 Accord - Spark Plug Replacement

Your Accord uses 4 spark plugs to ignite the air/fuel mixture. Over time they wear and can cause rough idle, misfires, and worse fuel economy. This job is straightforward because the plugs sit right on top of the engine under the ignition coils.

Difficulty Level: Beginner | Estimated Time: 0.8-1.5 hours

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⚠️ Safety & Precautions

• 🧯 Work on a fully cool engine to avoid burns and to protect the aluminum cylinder head threads.
• 🧤 Keep dirt out of the spark plug holes; debris can fall into the cylinder.
• 🔌 If you disconnect the battery: use a 10mm wrench and remove the negative terminal first.
• ⚡ Don’t pull on wiring; always unplug connectors by pressing the tab.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 1/4" drive ratchet
• 3/8" drive ratchet
• 3/8" drive extension set (3", 6")
• 10mm socket
• 5/8" spark plug socket
• Torque wrench (10-30 ft-lbs range)
• Flathead screwdriver
• Needle-nose pliers
• Feeler gauge (0.044" / 1.1 mm)
• Compressed air can
• Shop rags

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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 1st gear, and set the parking brake.
• ⏳ Let the engine cool completely (at least 1 hour after driving).
• 🧼 Wipe/blow off dust around the ignition coils so nothing falls into the plug wells.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Use a 10mm socket and 3/8" ratchet to remove the engine cover fasteners.
• Lift the cover off and set it aside.

Step 2: Unplug and remove the ignition coils

• On each coil, press the connector tab and unplug it (use a flathead screwdriver gently if the tab is stubborn).
• Use a 10mm socket and 1/4" ratchet to remove the coil hold-down bolt.
• Twist the coil slightly, then pull it straight up and out.
• Keep coils in order, 1 through 4.

Step 3: Clean the spark plug wells

• Use compressed air can to blow out each spark plug tube (the deep hole the coil came out of).
• Wipe around the top with shop rags.
• This prevents grit from falling in.

Step 4: Remove the old spark plugs

• Install a 5/8" spark plug socket on a 3/8" drive extension and 3/8" ratchet.
• Lower it straight into the tube and loosen the spark plug counterclockwise.
• Once loose, spin it out carefully and lift it out with the socket.
• If a plug feels extremely tight, stop and work it back-and-forth gently to avoid thread damage.

Step 5: Check the new plug gap (even if “pre-gapped”)

• Use a feeler gauge (0.044" / 1.1 mm) to confirm the gap on each new plug.
• If the gap is off, don’t force-bend the tiny center electrode on iridium plugs; exchange the plug instead.

Step 6: Install the new spark plugs (hand-thread first)

• Put one new plug into the 5/8" spark plug socket.
• Carefully lower it into the hole and turn it clockwise by hand using just the extension (no ratchet at first).
• Once it’s threaded smoothly, install the torque wrench and tighten to Torque to 18 Nm (13 ft-lbs).
• Hand-threading helps prevent cross-threading.

Step 7: Reinstall the ignition coils

• Apply a tiny amount of dielectric grease inside each coil boot (dielectric grease is a silicone grease that helps seal out moisture and eases future removal).
• Push each coil straight down until it fully seats on the spark plug.
• Reinstall each coil bolt with a 10mm socket, then tighten to Torque to 12 Nm (9 ft-lbs).
• Reconnect each coil electrical connector until it clicks.

Step 8: Reinstall the engine cover

• Reinstall the cover fasteners using a 10mm socket.
• Snug them evenly (do not over-tighten plastic cover hardware).

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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.
• 🧪 If it runs rough, shut it off and re-check that every coil connector is fully clicked in.
• 🚗 Take a short test drive, then recheck for any fuel smell or warning lights.

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💰 DIY vs Shop Cost

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

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

You Save: $130-$410 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.