🔧 Accord - Spark Plug Replacement

On your Accord, the spark plugs fire the air/fuel mixture. Worn plugs can cause rough idle, poor fuel economy, and misfires. This job is straightforward because the plugs sit right on top of the engine under the ignition coils.

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 damaged threads.
• ⚠️ Keep the ignition OFF and the key away from the car while unplugging coils.
• ⚠️ Don’t drop anything into the spark plug holes.
• ⚠️ No battery disconnect is required, but it’s okay to disconnect the negative terminal if you prefer extra safety.

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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" (16mm) spark plug socket
• Torque wrench (3/8" drive, 10-30 ft-lbs range)
• Flat trim tool
• Compressed air blow gun
• Shop vacuum
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (iridium) - Qty: 4
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground and let the engine cool completely.
• Open the hood and remove any loose jewelry or sleeves.
• If you choose to disconnect the battery: use a 10mm socket to remove the negative terminal and keep it from touching the post.

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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 to remove the engine cover nuts/bolts.
• Lift the cover off and set it aside.

Step 2: Unplug and remove ignition coils (one cylinder at a time)

• Pick one coil to start with so parts don’t get mixed up.
• Use a flat trim tool to gently help release the electrical connector lock (don’t pry hard).
• Pull the connector straight off the coil.
• Use a 10mm socket and 3/8" ratchet to remove the coil hold-down bolt.
• Twist the coil slightly, then pull it straight up and out of the plug well.
• One coil at a time prevents mix-ups.

Step 3: Clean out the spark plug well

• Use a shop vacuum to remove loose dirt around the plug opening.
• Use compressed air blow gun to blow debris out of the spark plug well before removing the plug.

Step 4: Remove the old spark plug

• Install the 5/8" (16mm) spark plug socket on a 3/8" extension and 3/8" ratchet.
• A spark plug socket is a deep socket with a rubber insert that grips the plug so it can lift out.
• Turn counterclockwise to loosen and remove the plug.
• Lift the plug out carefully with the socket.

Step 5: Install the new spark plug (by hand first)

• Compare the new plug to the old one to confirm the same length and seat style.
• Do not adjust the gap on iridium plugs (they’re designed to be installed as-is).
• Place the new plug into the 5/8" (16mm) spark plug socket.
• Thread it in by hand using only the 3/8" extension (no ratchet yet) until it seats. This helps prevent cross-threading.
• Attach the torque wrench and tighten: Torque to 18 N·m (13 ft-lbs).
• No anti-seize on Honda iridium plugs.

Step 6: Reinstall the ignition coil

• Optional: apply a tiny dab of dielectric grease inside the coil boot (it helps prevent moisture and makes future removal easier).
• Push the coil straight down until fully seated.
• Install the coil bolt using a 10mm socket, then tighten with a torque wrench: Torque to 12 N·m (9 ft-lbs).
• Reconnect the electrical connector until it clicks into place.

Step 7: Repeat for the remaining cylinders

• Repeat Steps 2 through 6 for the other three spark plugs.

Step 8: Reinstall the engine cover

• Set the cover back in place.
• Use a 10mm socket to tighten the cover fasteners snugly.

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✅ After Repair

• Start the engine and let it idle for 30-60 seconds. It should run smooth.
• If the check engine light comes on or it runs rough: shut it off and recheck each coil connector is fully clicked in.
• Take a short test drive and confirm normal power and no flashing check engine light.

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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.