🔧 Insight - Spark Plug Replacement

You’ll be removing the ignition coils, taking out the old spark plugs, and installing new ones with the correct torque. Fresh spark plugs help prevent misfires, rough running, and poor fuel economy.

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

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and damaged threads.
• ⚠️ Power the car OFF and keep the key fob at least 10 feet away so the hybrid system can’t wake up.
• ⚠️ Do not drop anything into the spark plug tubes; dirt can damage the engine.
• ⚠️ Battery disconnect is not required for this job, but never unplug high-voltage orange cables.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 10mm socket
• 3/8" ratchet
• 3/8" extension set (3" and 6")
• 14mm thin-wall spark plug socket (rubber insert)
• Torque wrench 3/8" drive (10-30 Nm range)
• Small flat trim tool
• Compressed air blow gun
• Clean shop towels
• Flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

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

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📋 Before You Begin

• Park on level ground and press the brake, then power the car OFF.
• Open the hood and let the engine cool completely (at least 30-60 minutes).
• Set your tools out in order 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

• Use a small flat trim tool and your hands to lift the engine cover straight up and off (it’s held by rubber grommets).
• Set the cover aside where it won’t get stepped on.

Step 2: Unplug the ignition coils

• Locate the ignition coil connectors (one per cylinder on top of the engine).
• Press the connector lock tab by hand and pull the connector straight off. Use a small flat trim tool gently only if the tab is stubborn.
• Don’t yank on the wires.

Step 3: Remove the ignition coils

• Remove each coil hold-down bolt using a 10mm socket and 3/8" ratchet.
• Twist the coil slightly, then pull straight upward to remove it from the spark plug tube.
• Place the coils in order (cylinder 1-4) so they go back where they came from.

Step 4: Clean the spark plug wells

• Blow out each spark plug tube using a compressed air blow gun.
• Wipe around the tube openings with clean shop towels.
• This prevents dirt from falling into the cylinder.

Step 5: Remove the old spark plugs

• Install the 14mm thin-wall spark plug socket (rubber insert) on a 3/8" extension and 3/8" ratchet.
• Loosen each spark plug counterclockwise and remove it carefully from the tube.
• If a plug feels extremely tight, stop and re-check the socket is fully seated before forcing it.

Step 6: Install the new spark plugs (hand-thread first)

• Confirm the new plugs match the old ones in length and seat style.
• Put the new plug into the spark plug socket, then lower it into the tube with a 3/8" extension only (no ratchet yet).
• Thread it in by hand using the extension until it seats. It should spin in smoothly most of the way.
• Do not use anti-seize unless the spark plug maker specifically says to.

Step 7: Torque the spark plugs

• Set your torque wrench 3/8" drive (10-30 Nm range).
• Tighten each spark plug to Torque to 18 Nm (13 ft-lbs).
• Correct torque prevents stripped threads.

Step 8: Reinstall ignition coils

• Apply a tiny smear of dielectric grease inside each coil boot (the rubber end that snaps onto the plug). Dielectric grease is a non-conductive grease that helps prevent moisture and makes removal easier later.
• Push each coil straight down until you feel it fully seat on the spark plug.
• Install coil bolts using a 10mm socket and then torque with a torque wrench to Torque to 12 Nm (9 ft-lbs).

Step 9: Plug the coil connectors back in

• Push each connector on by hand until it clicks/locks.
• Do a quick visual check that no wiring is pinched.

Step 10: Reinstall the engine cover

• Line the cover up with its mounting points and press down firmly by hand until it seats.

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✅ After Repair

• Start your Insight and let it idle. It should run smooth with no shaking.
• Watch the dash for a check engine light or misfire warning.
• Take a short test drive and recheck for any odd smell, ticking, or roughness.
• If you had a misfire code before, clear codes with a scan tool and confirm it doesn’t return.

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💰 DIY vs Shop Cost

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

DIY Cost: $60-$140 (parts only)

You Save: $190-$310 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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