🔧 Fit - Spark Plug Replacement

Changing the spark plugs on your Fit restores clean ignition, smooth idle, fuel economy, and proper engine performance. The 1.5L engine uses four ignition coils, one on top of each spark plug, and each plug is replaced from the top of the engine.

Difficulty Level: Beginner | Estimated Time: 1-2 hours

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⚠️ Safety & Precautions

• ⚠️ Work only on a completely cool engine to avoid damaging the aluminum cylinder head threads.
• ⚠️ Disconnect the negative battery terminal before unplugging ignition coils.
• ⚠️ Do not drop anything into the spark plug wells; debris can fall into the engine.
• ⚠️ Start each new spark plug by hand first to prevent cross-threading.
• ⚠️ Use only the correct iridium spark plugs; do not install copper plugs.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 3/8-inch drive ratchet
• 3/8-inch drive extension 6-inch
• 5/8-inch spark plug socket
• Torque wrench 3/8-inch drive
• Flathead screwdriver small
• Compressed air nozzle
• Spark plug gap gauge
• Dielectric grease
• Mechanic gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs - Qty: 4

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📋 Before You Begin

• Park your Fit on level ground and set the parking brake.
• Let the engine cool fully before removing the spark plugs.
• Open the hood and make sure the work area is well lit.
• Use a 10mm socket to disconnect the negative battery terminal, then move the cable aside so it cannot touch the battery post.
• A spark plug socket is a deep socket with a rubber insert or magnet that holds the spark plug while you lift it out.
• A torque wrench tightens bolts or spark plugs to a measured amount so they are not too loose or too tight.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the Engine Cover Area Obstructions

• Put on safety glasses and mechanic gloves.
• If equipped with small plastic covers over the ignition coil area, remove them by hand or use a small flathead screwdriver to release the clips gently.
• Set any clips or covers aside in order so they go back in the same place.
• Take a phone photo first.

Step 2: Clean Around the Ignition Coils

• Use a compressed air nozzle to blow dust and grit away from the top of the engine around the four ignition coils.
• Do not aim debris toward your face; keep safety glasses on.
• This helps prevent dirt from falling into the spark plug holes.

Step 3: Unplug the First Ignition Coil

• Work on one spark plug at a time so parts do not get mixed up.
• Use your fingers to press the electrical connector lock tab on the first ignition coil.
• If the connector is stiff, use a small flathead screwdriver to gently lift the lock tab while pulling the connector straight back.
• An ignition coil is the small electrical part that sits directly on top of each spark plug and sends high voltage to fire it.

Step 4: Remove the Ignition Coil Bolt

• Use a 10mm socket with a 3/8-inch drive ratchet to remove the ignition coil hold-down bolt.
• Place the bolt in a safe spot.
• Grip the ignition coil by hand and twist it slightly to loosen the rubber boot.
• Pull the ignition coil straight up and out.

Step 5: Remove the Old Spark Plug

• Use a 5/8-inch spark plug socket, 6-inch extension, and 3/8-inch drive ratchet.
• Lower the socket straight down into the spark plug well until it seats on the spark plug.
• Turn counterclockwise slowly to loosen the spark plug.
• Once loose, spin it out carefully and lift it out with the spark plug socket.
• If it feels stuck, stop and tighten it slightly, then loosen again gently.
• Never force a stuck plug.

Step 6: Check the New Spark Plug

• Use a spark plug gap gauge to verify the new plug gap is correct for the Fit before installation.
• Most correct iridium replacement plugs come pre-gapped, but check that the electrode was not bent in shipping.
• Do not pry on the fine iridium center tip.
• Do not apply anti-seize unless the spark plug manufacturer specifically says to use it.

Step 7: Install the New Spark Plug by Hand

• Place the new spark plug into the 5/8-inch spark plug socket.
• Use the 6-inch extension only, without the ratchet, to lower the plug into the well.
• Turn clockwise by hand for several full turns.
• If it does not turn smoothly, remove it and start again.
• This prevents cross-threading, which means the plug is going in crooked and can damage the cylinder head.

Step 8: Torque the New Spark Plug

• Attach a 3/8-inch drive torque wrench to the 6-inch extension and 5/8-inch spark plug socket.
• Tighten the spark plug to Torque to 18 Nm (13 ft-lbs).
• Stop as soon as the torque wrench clicks.
• One click is enough.

Step 9: Reinstall the Ignition Coil

• Apply a very small amount of dielectric grease inside the end of the ignition coil boot.
• Dielectric grease is a non-conductive silicone grease that helps keep moisture out of the rubber boot.
• Push the ignition coil straight down onto the new spark plug until it seats fully.
• Install the ignition coil bolt by hand first.
• Use a 10mm socket and torque wrench to tighten the ignition coil bolt to Torque to 12 Nm (9 ft-lbs).

Step 10: Reconnect the Ignition Coil Connector

• Push the electrical connector onto the ignition coil by hand until it clicks.
• Lightly tug the connector to make sure it is locked.

Step 11: Repeat for the Other Three Spark Plugs

• Repeat Steps 3 through 10 for the remaining three ignition coils and spark plugs.
• Use the 10mm socket for each coil bolt.
• Use the 5/8-inch spark plug socket, 6-inch extension, ratchet, and torque wrench for each spark plug.
• Replace all four spark plugs during the same service.

Step 12: Reinstall Covers and Reconnect the Battery

• Reinstall any removed plastic covers or clips by hand.
• Use a 10mm socket to reconnect the negative battery terminal.
• Tighten the terminal snugly; do not overtighten.

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✅ After Repair

• Start your Fit and let it idle for 1-2 minutes.
• Listen for a smooth idle with no shaking or misfire.
• If the engine runs rough, shut it off and check that all four ignition coil connectors are fully clicked in.
• Take a short test drive and confirm smooth acceleration.
• If the battery was disconnected, reset the clock and radio presets if needed.
• If the check engine light was on before the repair, it may need to be cleared with a scan tool after confirming the misfire is fixed.

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💰 DIY vs Shop Cost

Shop Cost: $180-$350 (parts + labor)

DIY Cost: $45-$100 (parts only)

You Save: $135-$250 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?

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