🔧 Accord - Spark Plug Replacement

On your Accord, the spark plugs fire the air/fuel mix in the engine. Replacing them restores smooth idle, fuel economy, and prevents misfires as the plugs wear.

Difficulty Level: Beginner | Estimated Time: 1.0-2.0 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 plug wells—debris can fall into the cylinder and cause damage.
• ⚠️ Do not over-tighten spark plugs; the head is aluminum and threads can strip.
• ⚠️ Battery disconnect is not required, but keep the key away from the car and don’t crank the engine with any ignition coils unplugged.

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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" and 6")
• 10mm socket
• 5/8" (16mm) spark plug socket
• 3/8" drive torque wrench (ft-lb range)
• Small flat trim tool
• Compressed air blow gun
• Clean shop towels
• Dielectric grease

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (OEM-spec) - Qty: 4
• Ignition coil boots - Qty: 4 (only if boots are torn/oil-soaked)

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Let the engine cool completely (ideally 1+ hour after driving).
• Set your tools on a clean surface so nothing falls into the engine bay.

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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 1/4" drive ratchet to remove the engine cover fasteners.
• Lift the cover straight up and set it aside.

Step 2: Unplug the first ignition coil

• Find the ignition coils on top of the engine (one per cylinder).
• Use a small flat trim tool to gently release the electrical connector lock tab, then pull the connector off.
• Do one cylinder at a time.

Step 3: Remove the ignition coil

• Use a 10mm socket with a 1/4" drive ratchet to remove the coil hold-down bolt.
• Twist the coil slightly, then pull it straight up to remove it.
• Wipe the coil boot with a clean shop towel. If you see engine oil inside the plug tube, stop and tell me—there may be a valve cover tube seal leak.

Step 4: Clean the spark plug well

• Use compressed air blow gun to blow out dirt around the spark plug before loosening it.
• Aim away from your face and wear safety glasses.

Step 5: Remove the spark plug

• Install the 5/8" (16mm) spark plug socket on a 3/8" drive extension and 3/8" drive ratchet.
• Lower the socket straight down onto the plug, then loosen and remove the spark plug.
• If it feels extremely tight, stop and tell me—forcing it on a warm engine can damage threads.

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

• Put the new plug into the spark plug socket so it stays straight.
• Thread it in by hand using only the extension (no ratchet at first) until fully seated. This helps prevent cross-threading (threading in crooked).
• Do not use anti-seize unless the plug maker specifically calls for it.

Step 7: Torque the spark plug

• Set your 3/8" drive torque wrench (ft-lb range) to the correct spec. (A torque wrench is a tool that clicks at a set tightness so you don’t over-tighten.)
• Tighten the plug to Torque to 18 Nm (13 ft-lbs).

Step 8: Reinstall the ignition coil

• Add a very small smear of dielectric grease inside the end of the coil boot.
• Push the coil straight down until fully seated on the plug.
• Install the coil bolt using a 10mm socket and 1/4" drive ratchet, then tighten to Torque to 12 Nm (9 ft-lbs).
• Reconnect the coil electrical connector until it clicks.

Step 9: Repeat for the other 3 cylinders

• Repeat Steps 2–8 for each remaining ignition coil and spark plug.
• Keep parts grouped per cylinder.

Step 10: Reinstall engine cover and final check

• Reinstall the engine cover using the 10mm socket and 1/4" drive ratchet.
• Do a quick visual check that all 4 coil connectors are fully locked in.

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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 clicked in and each coil bolt is installed.
• Take a short test drive, then re-check for any unusual smells or noises.

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💰 DIY vs Shop Cost

Shop Cost: $220-$400 (parts + labor)

DIY Cost: $45-$110 (parts only)

You Save: $110-$300 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?

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