🔧 Accord - Spark Plug Replacement

Your Accord’s spark plugs wear over time, which can cause misfires, rough idle, poor fuel economy, and hard starts. On the 2.4L engine, the plugs are easy to access on top of the engine under the ignition coils.

Difficulty Level: Beginner | Estimated Time: 0.7-1.5 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a cold engine to avoid burns and damaged threads.
• ⚠️ Keep dirt out of the spark plug holes (it can damage the engine).
• ⚠️ Do not pull on wires; unplug connectors by the plastic tab.
• Battery disconnect is not required, but keep the key out of the ignition.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 3/8" drive ratchet
• 3/8" drive extension set (3" and 6")
• 5/8" spark plug socket (rubber insert or magnetic)
• Torque wrench (3/8" drive, inch-pound/foot-pound)
• Flat trim tool
• Compressed air blow gun
• Feeler gauge set
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (iridium/platinum, correct fit for 2.4L) - Qty: 4
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, transmission in neutral, parking brake set.
• Let the engine cool fully (at least 30–60 minutes after driving).
• Lay out 4 new spark plugs and keep them clean and unopened until needed.

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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" drive ratchet to remove the cover fasteners.
• Lift the cover off and set it aside.

Step 2: Unplug and remove ignition coil #1

• Press the connector tab and unplug the coil using a flat trim tool if needed to gently help release it.
• Remove the coil hold-down bolt using a 10mm socket and 3/8" drive ratchet.
• Twist the coil boot slightly, then pull the coil straight up and out.
• One coil at a time prevents mix-ups.

Step 3: Blow out the spark plug well

• Wear safety glasses.
• Use compressed air blow gun to blow dirt out of the spark plug tube (the deep hole).
• This prevents debris from falling into the cylinder when the plug is removed.

Step 4: Remove the old spark plug

• Install a 5/8" spark plug socket on a 3/8" drive extension (6") and 3/8" drive ratchet.
• Lower the socket straight down onto the plug and loosen it counterclockwise.
• Lift the plug out with the socket.

Step 5: Check the new spark plug gap (only verify)

• Use a feeler gauge set to confirm the gap matches the plug spec listed on the box.
• Do not bend the tiny center tip on iridium plugs; if the gap is off, exchange the plug.

Step 6: Install the new spark plug

• Place the new plug into the 5/8" spark plug socket and lower it straight into the hole using a 3/8" drive extension (6").
• Thread the plug in by hand first using only the extension (no ratchet) until it seats. This helps avoid cross-threading (damaging the threads).
• Tighten with a torque wrench (3/8" drive): Torque to 18 N·m (13 ft-lbs).
• Do not use anti-seize on the plug threads.

Step 7: Reinstall the ignition coil

• Apply a tiny dab of dielectric grease inside the coil boot (the rubber “socket” that snaps onto the plug).
• Push the coil straight down until it fully seats on the spark plug.
• Install the coil bolt using a 10mm socket and torque wrench (3/8" drive): Torque to 12 N·m (9 ft-lbs).
• Plug the connector back in until it clicks.

Step 8: Repeat for cylinders 2–4

• Repeat Steps 2–7 for each remaining coil and plug.
• Keep the process “one coil, one plug” to stay organized.

Step 9: Reinstall the engine cover (if equipped)

• Set the cover back on.
• Tighten the fasteners using a 10mm socket and 3/8" drive ratchet.

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✅ After Repair

• Start the engine and let it idle for 30–60 seconds. It should run smooth.
• Listen for a steady idle (no shaking) and make sure the check engine light stays off.
• Take a short test drive and re-check for any roughness under acceleration.
• If you get a misfire after this job, re-check coil connectors are fully clicked in.

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💰 DIY vs Shop Cost

Shop Cost: $200-$450 (parts + labor)

DIY Cost: $35-$90 (parts only)

You Save: $165-$360 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.7-1.5 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.