🔧 Crosstrek - Spark Plug Replacement

On your Crosstrek, the spark plugs sit on the sides of the engine (it’s a “boxer” engine), so access is tighter than many cars. You’ll remove a few nearby items for room, then swap all 4 plugs carefully to avoid damaging the aluminum cylinder heads.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.0 hours

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⚠️ Safety & Precautions

• Work on a fully cool engine (hot aluminum threads strip easily).
• Do not cross-thread spark plugs—always start threading by hand first.
• Keep dirt out of the spark plug holes; blow debris away before removing plugs.
• Avoid anti-seize on plug threads unless the plug maker specifically requires it (most modern plugs are plated).
• Battery disconnect is not required, but disconnecting the negative terminal is a good safety step if you’re nervous around wiring.

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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" torque wrench (10–30 ft-lbs range)
• 3/8" extension set (3", 6", 10")
• 3/8" universal joint swivel
• 14mm spark plug socket (thin-wall, with rubber insert)
• Flathead screwdriver
• Needle-nose pliers
• Compressed air or hand air blower
• Flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (iridium/platinum, correct fit for 2.0L) - Qty: 4
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and let the engine cool completely.
• Open the hood and remove any loose items near the battery and air box.
• If you choose to disconnect the battery: use a 10mm socket to remove the negative terminal and tuck it aside so it can’t spring back.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Create working room (battery side)

• On the battery side, remove the battery hold-down and move the battery out for access using a 10mm socket and needle-nose pliers (for any clips).
• Set the battery somewhere safe and upright.

Step 2: Create working room (air box side)

• Loosen the intake hose clamp(s) with a flathead screwdriver.
• Unclip/unbolt the air cleaner housing as needed using a 10mm socket, then lift it out to open up space near the side of the engine.

Step 3: Unplug and remove the ignition coil (one cylinder at a time)

• Locate an ignition coil (the small module bolted near each spark plug).
• Press the electrical connector tab and unplug it (use a flashlight to see the lock tab clearly).
• Remove the coil retaining bolt with a 10mm socket.
• Twist the coil gently and pull it straight out.
• Do one plug at a time to avoid mix-ups.

Step 4: Clean the plug well

• Blow out the area around the spark plug hole using compressed air or hand air blower.
• This helps keep grit from falling into the cylinder.

Step 5: Remove the old spark plug

• Install the 14mm spark plug socket (thin-wall, with rubber insert) on a 3/8" ratchet with the needed 3/8" extensions and a 3/8" universal joint swivel.
• Break the plug loose and remove it slowly.
• If it feels stuck, stop and re-tighten slightly, then loosen again (this reduces thread damage risk).

Step 6: Install the new spark plug (hand-start first)

• Confirm the new plug matches the old one (same length and tip style).
• Place the new plug in the 14mm spark plug socket and carefully thread it in by hand using only the extension (no ratchet yet) until it seats.
• Tighten with a 3/8" torque wrench: Torque to 21 Nm (15 ft-lbs).
• Do not adjust the gap on fine-wire iridium plugs.

Step 7: Reinstall the ignition coil

• Put a small smear of dielectric grease inside the coil boot (the rubber part) to help prevent moisture and make future removal easier.
• Push the coil straight onto the plug until fully seated.
• Install the coil bolt using a 10mm socket, then finish with a 3/8" torque wrench: Torque to 7.5 Nm (5.5 ft-lbs).
• Reconnect the electrical connector until it clicks.

Step 8: Repeat for the remaining 3 spark plugs

• Repeat Steps 3–7 for each cylinder, moving one at a time.
• Use the flashlight often—space is tight and visibility is limited.

Step 9: Reassemble intake and battery

• Reinstall the air box and intake ducting using a 10mm socket and flathead screwdriver for clamps.
• Reinstall the battery and hold-down using a 10mm socket.
• If disconnected, reconnect the negative battery terminal using a 10mm socket.

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✅ After Repair

• Start the engine and let it idle for 1–2 minutes. It should run smooth with no flashing check-engine light.
• If the engine runs rough: shut it off and re-check that every coil connector is fully clicked in.
• Take a short test drive and re-check for any intake hose clamps left loose.

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💰 DIY vs Shop Cost

Shop Cost: $280-$450 (parts + labor)

DIY Cost: $40-$90 (parts only)

You Save: $240-$360 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-2.5 hours.

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🎯 Ready to get started?

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