🔧 ILX - Spark Plug Replacement

On your ILX, the spark plugs sit under the ignition coils on top of the engine. Replacing them restores smooth starting, idle quality, and fuel economy, and prevents misfires as mileage climbs.

Difficulty Level: Intermediate | Estimated Time: 1.0-2.0 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a cool engine to avoid burns and damaged threads.
• ⚠️ Keep dirt out of the spark plug holes; debris can damage the engine.
• ⚠️ Do not pull on wires; unplug coils by the connector only.
• ⚠️ Battery disconnect is not required, but it’s okay to disconnect the negative terminal if you’re worried about shorting tools.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 3/8" drive ratchet
• 3/8" drive torque wrench (5-30 ft-lbs range)
• 6" extension (3/8" drive)
• 12" extension (3/8" drive)
• 5/8" spark plug socket (rubber insert or magnetic)
• Flat trim tool
• Compressed air blow gun
• Feeler gauge set (inch)
• Small pick tool
• Flashlight
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

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

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Let the engine cool fully (at least 30-60 minutes after driving).
• Lay out the new plugs and keep them clean; don’t drop them.
• A spark plug “torque” is twist-tightness.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover (if equipped)

• Use a flat trim tool to gently lift the cover corners if it’s clipped on, then pull it up evenly.
• Set the cover aside where it won’t get stepped on.

Step 2: Unplug and remove ignition coils

• Locate the 4 ignition coils on top of the engine (one per cylinder).
• Press the electrical connector tab and unplug each coil; use a small pick tool only if the tab is stuck. Don’t break the lock tab.
• Use a 10mm socket with a 3/8" drive ratchet to remove the bolt holding each coil.
• Twist the coil slightly and pull it straight up to remove it.
• Keep coils in order (set them in a row) so they go back to the same cylinder.
• When reinstalling the coil bolts later: Torque to 12 Nm (9 ft-lbs)

Step 3: Clean around the spark plug wells

• Use compressed air blow gun and safety glasses to blow dirt out of each spark plug tube.
• This prevents grit from falling into the cylinder when the plug comes out.

Step 4: Remove the old spark plugs

• Install the 5/8" spark plug socket on a 6" extension (use the 12" extension if needed), then attach the 3/8" drive ratchet.
• Lower the socket straight down onto the spark plug until fully seated.
• Turn counterclockwise to loosen, then spin the plug out carefully.
• Lift the plug out with the socket; use a flashlight to confirm the hole is clean.

Step 5: Check the new spark plugs (gap and condition)

• Use a feeler gauge set (inch) to verify the plug gap matches OEM spec for your ILX.
• If the plugs are iridium (common on this engine), do not bend the tiny center tip; if the gap is off, exchange the plug rather than forcing it.

Step 6: Install the new spark plugs by hand first

• Place a new plug into the 5/8" spark plug socket.
• Carefully lower it into the hole and thread it in by hand using the extension only (no ratchet yet).
• It should spin smoothly; if it feels tight right away, back it out and start again (this avoids cross-threading).
• Once seated, use the 3/8" drive torque wrench to tighten: Torque to 18 Nm (13 ft-lbs)
• Skip anti-seize unless the plug maker requires it.

Step 7: Reinstall ignition coils and connectors

• If using it, apply a tiny amount of dielectric grease inside the end of each coil boot (this helps prevent moisture sticking). Dielectric grease is a non-conductive silicone grease.
• Push each coil straight down until fully seated.
• Install the coil bolts using a 10mm socket, then finish with a 3/8" drive torque wrench: Torque to 12 Nm (9 ft-lbs)
• Plug the electrical connectors back in until they click.

Step 8: Reinstall the engine cover

• Align the cover and press down evenly until it seats.

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✅ After Repair

• Start the engine and let it idle for 30-60 seconds; it should run smooth.
• Listen for a misfire (shaking, popping) and re-check coil connectors if anything feels off.
• Take a short test drive, then re-check for any warning lights.

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💰 DIY vs Shop Cost

Shop Cost: $250-$450 (parts + labor)

DIY Cost: $40-$120 (parts only)

You Save: $210-$330 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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