2019 Subaru Crosstrek Spark Plug Specifications

Quick Reference: 2019 Subaru Crosstrek Spark Plugs

Why the Right Spark Plug Matters

Choosing the correct spark plug isn't just about finding one that threads in; it's critical for engine performance, efficiency, and longevity. The 2019 Crosstrek's 2.0L FB20D engine is designed from the factory for long-life iridium-tipped spark plugs, and using a lesser plug can cause a host of problems.

• Heat Range: This is a plug's ability to dissipate heat. A plug that is too "hot" (doesn't dissipate heat well) can lead to pre-ignition (detonation), which can cause catastrophic engine damage. A plug that is too "cold" can accumulate carbon deposits, leading to misfires. The factory-specified NGK plug has the correct heat range engineered for the Crosstrek's combustion chamber temperatures and operating conditions.
• Electrode Material: The FB20D engine uses iridium-tipped fine-wire spark plugs for a reason. Iridium is an extremely hard and dense precious metal, allowing for a very small center electrode. This sharp point requires less voltage to create a spark, resulting in a more consistent and stable idle, better throttle response, and improved cold starting. While cheaper platinum or copper plugs might fit, they will wear out much faster and may not perform as well, potentially reducing fuel economy and causing misfires long before the 60,000-mile interval is up.

How to Gap a Spark Plug

Properly gapping a spark plug is crucial. The gap is the distance between the center and ground electrodes; if it's too small, the spark can be weak, and if it's too large, it may fail to fire at all under high load.

Iridium plugs, like those specified for the Crosstrek, come pre-gapped from the factory. You should always verify the gap, but be extremely careful. The fine-wire iridium center electrode is very brittle and can easily snap.

1. Use the Right Tool: Never use a cheap "coin-style" gapper. Use a feeler gauge or a dedicated wire-loop gapping tool.
2. Check the Gap: Gently slide the 0.032" (0.8mm) wire or blade of your gauge between the electrodes. It should slide through with very slight resistance. Don't force it.
3. Adjust Carefully: If adjustment is needed, do not pry against the center electrode. Instead, gently bend the ground strap (the J-shaped electrode) up or down using the adjustment slot on your gapping tool or a pair of needle-nose pliers. Make tiny adjustments and re-check frequently until the gap is correct.

Replacement Procedure Tips for FB20D Engine

Subaru's boxer engine design places the spark plugs on the side of the engine, which can make access a bit more challenging than on an inline or V-type engine. However, it's a manageable DIY job.

• Coil-on-Plug Removal: The Crosstrek uses a modern coil-on-plug ignition system. Each spark plug has its own ignition coil sitting directly on top of it. To access the plug, you must first unplug the electrical connector from the coil and then remove the single 10mm bolt holding the coil to the valve cover. The coil can then be gently twisted and pulled straight out. The rubber boot can sometimes stick to the spark plug, so a firm, steady pull is key.
• The Anti-Seize Debate: This is a hot topic. NGK, the OEM plug manufacturer, explicitly advises against using anti-seize on their modern plugs. The plugs have a special trivalent plating that acts as its own anti-seize and provides a specific level of friction for accurate torqueing. Adding anti-seize lubricant can act as a multiplier, causing you to over-torque the spark plug. Over-torqueing can stretch the plug's metal shell and damage the internal seals, or worse, damage the threads in the aluminum cylinder head.
• Dielectric Grease: While anti-seize on the threads is a no-go, applying a small amount of dielectric grease to the inside of the ignition coil boot is highly recommended. This prevents the boot from sticking to the new spark plug's ceramic insulator, prevents voltage leaks, and seals out moisture, making future removal much easier.

Known Issues

Fortunately, the 2019 Subaru Crosstrek and its FB20D engine are not known for widespread, systemic spark plug issues like the infamous Ford 3-valve Triton plug breakage. The design is robust and conventional. By using the correct OEM-spec NGK iridium plug, torquing it to the specified 13 lb-ft, and adhering to the 60,000-mile replacement interval, you can expect reliable performance without trouble.

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