🔧 CX-5 - Spark Plug Replacement

On your CX-5, the spark plugs sit under the ignition coils on top of the engine. Replacing them restores smooth starting, power, and fuel economy, especially if you’re due by mileage or feeling a misfire/rough idle.

Difficulty Level: Intermediate | Estimated Time: 1.0-1.5 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a completely 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.
• ⚠️ Optional but recommended: disconnect the negative battery cable to prevent accidental electrical shorts.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 1/4" drive ratchet
• 3/8" drive ratchet
• 3/8" drive torque wrench (5–40 Nm range)
• 3/8" extension set (3" and 6")
• 14mm spark plug socket (rubber insert)
• Flat trim tool
• Compressed air blow gun
• Feeler gauge (0.044 in / 1.1 mm)
• Dielectric grease
• Nitrile gloves
• Safety glasses

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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 (optional, if torn/oil-soaked) - Qty: 4

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📋 Before You Begin

• Park on level ground, set the parking brake, and open the hood.
• Let the engine cool fully (at least 1 hour after driving).
• If disconnecting the battery: use a 10mm socket to remove the negative cable and isolate it 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

• Lift the engine cover straight up by hand to pop it off its rubber grommets.

Step 2: Unplug and remove the ignition coils

• Unplug each ignition coil electrical connector (use a flat trim tool to gently lift the lock tab if it’s stubborn).
• Remove the coil hold-down bolt using a 10mm socket and 1/4" drive ratchet.
• Twist the coil slightly and pull it straight up to remove it.
• Keep coils in order, one per cylinder.

Step 3: Clean the spark plug wells

• Use compressed air blow gun to blow out dirt around each spark plug hole before removing the plug.
• Wear safety glasses so debris doesn’t blow into your eyes.

Step 4: Remove the old spark plugs

• Use a 14mm spark plug socket (rubber insert), 3/8" drive extension, and 3/8" drive ratchet to loosen and remove each spark plug.
• If a plug feels extremely tight, stop and work it back-and-forth gently to avoid thread damage.

Step 5: Check the new spark plug gap (only if specified by the plug maker)

• Use a feeler gauge (0.044 in / 1.1 mm) to verify the gap matches the plug’s specification.
• Most OEM-style iridium plugs are pre-gapped; do not force-bend the fine iridium tip.

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

• Place a new plug into the 14mm spark plug socket and lower it into the hole with the 3/8" extension.
• Thread it in by hand using the extension only (no ratchet) until it seats.
• This prevents cross-threading (starting threads crooked).

Step 7: Torque the spark plugs

• Use a 3/8" drive torque wrench to tighten each spark plug.
• Torque to 15–20 Nm (11–15 ft-lbs)

Step 8: Reinstall ignition coils

• Apply a tiny smear of dielectric grease inside each coil boot (this helps prevent moisture and makes future removal easier).
• Push each coil straight down until fully seated.
• Install the coil bolt using a 10mm socket.
• Torque to 8–10 Nm (71–88 in-lbs)
• Reconnect each electrical connector until it clicks.

Step 9: Reinstall the engine cover

• Align the cover to the mounting points and press down firmly by hand until it snaps into place.

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✅ After Repair

• If you disconnected the battery, reconnect the negative cable using a 10mm socket and tighten snugly.
• Start the engine and let it idle for 30–60 seconds; it should run smooth with no shaking.
• Listen for ticking/air leaks and confirm no warning lights appear.
• If you had a misfire before and it remains, swap coil positions to see if the misfire follows a coil (helps diagnose a bad coil).

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💰 DIY vs Shop Cost

Shop Cost: $200-$400 (parts + labor)

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

You Save: $160-$280 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?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.