🔧 Fit - Spark Plug Replacement

On your Fit, the spark plugs sit under the ignition coils on top of the engine. Replacing them restores strong spark, helps prevent misfires, and keeps fuel economy and starting performance where it should be.

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 prevent damaging aluminum threads.
• ⚠️ Keep dirt out of the spark plug holes—debris can fall into the cylinder and cause engine damage.
• ⚠️ Do not over-tighten spark plugs; the cylinder head is aluminum and threads can strip.
• ⚠️ Battery disconnect is not required, but if you disconnect it, use a 10mm wrench on the negative terminal and be ready to reset the clock/radio settings.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 10mm socket
• 3/8" drive ratchet
• 3/8" drive extension (6")
• 16mm spark plug socket (5/8")
• Torque wrench (3/8" drive, 10-30 ft-lbs range)
• Small flat trim tool
• Compressed air or blower
• Feeler gauge set (0.030"-0.060")
• Flashlight
• Dielectric grease

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (OEM-equivalent iridium/platinum for your Fit) - Qty: 4

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📋 Before You Begin

• Park on level ground, shift into 1st gear, and set the parking brake.
• Let the engine cool completely (best: sit 1+ hour).
• Open the hood and have your flashlight ready so you can clearly see each coil and plug well.
• If you choose to disconnect the battery: loosen the negative terminal with a 10mm socket and move it aside so it can’t spring back.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Use a small flat trim tool to gently pop up any plastic clips, then lift the cover off by hand.

Step 2: Unplug the ignition coil connector (one cylinder at a time)

• Locate the first ignition coil on top of the engine.
• Press the connector lock tab and pull the connector straight off by hand. If it’s stuck, use a small flat trim tool gently—don’t pry hard.
• Do one coil/plug at a time to avoid mix-ups.

Step 3: Remove the ignition coil

• Remove the coil hold-down bolt using a 10mm socket and 3/8" drive ratchet.
• Lift the coil straight up. If it feels stuck, twist it slightly by hand while pulling up.
• Torque to 12 Nm (9 ft-lbs) when reinstalling the coil bolt.
• Ignition coil = the part that sits on the plug.

Step 4: Blow out the spark plug well

• Use compressed air or blower to clear dust/debris from around the spark plug before removing it.
• This prevents dirt from falling into the engine.

Step 5: Remove the spark plug

• Install the 16mm spark plug socket (5/8") onto a 3/8" drive extension (6") and 3/8" drive ratchet.
• Turn counterclockwise to loosen, then remove the plug completely.
• If it feels extremely tight, stop and re-check that the engine is cool.

Step 6: Check the new spark plug gap

• Use a feeler gauge set to confirm the gap matches the spec on the plug box for your Fit’s engine.
• Do not bend/pry on the center electrode of iridium plugs; if the gap is wrong, exchange the plug.
• Gap = the tiny space the spark jumps across.

Step 7: Install the new spark plug (start by hand)

• Place the new plug into the 16mm spark plug socket (5/8").
• Lower it into the hole and start threading it by hand using only the extension (no ratchet at first).
• If it doesn’t thread smoothly, back it out and restart—don’t force it.
• Tighten with a torque wrench: Torque to 18 Nm (13 ft-lbs).

Step 8: Reinstall the ignition coil

• Apply a tiny smear of dielectric grease inside the rubber coil boot (the rubber “cup” that slides onto the plug). Dielectric grease helps prevent moisture and sticking.
• Push the coil straight down until it fully seats on the plug.
• Install the coil bolt with a 10mm socket and snug it, then use a torque wrench: Torque to 12 Nm (9 ft-lbs).
• Plug the connector back in until it clicks.

Step 9: Repeat for the remaining cylinders

• Repeat Steps 2 through 8 for the other 3 spark plugs.

Step 10: Reinstall the engine cover and final check

• Reinstall the engine cover by hand and re-seat any clips using the small flat trim tool if needed.
• If you disconnected the battery, reconnect and tighten with a 10mm socket.

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✅ After Repair

• Start the engine and let it idle for 30-60 seconds. It should idle smooth with no shaking.
• If the check engine light comes on or it runs rough, shut it off and re-check that each coil connector is fully clicked in.
• Take a short test drive, then re-check for any unusual hesitation.

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💰 DIY vs Shop Cost

Shop Cost: $220-$420 (parts + labor)

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

You Save: $130-$330 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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