2023 Subaru Crosstrek Spark Plug Type & Gap

Quick reference

Why the right plug matters

The spark plugs in your 2023 Subaru Crosstrek are crucial for optimal engine performance and fuel efficiency. Using the correct spark plug type, heat range, and gap specified by Subaru is paramount.

Heat Range: Spark plugs are designed with a specific "heat range" to operate within an optimal temperature window. A plug that runs too hot can pre-ignite the fuel mixture, causing harmful "pinging" or detonation and leading to engine damage. A plug that runs too cold can foul with carbon deposits, leading to misfires and poor performance. Subaru has carefully selected a plug with the ideal heat range for your Crosstrek's engine.

Electrode Metal: Modern vehicles, like your Crosstrek, almost exclusively use long-life iridium-tipped spark plugs. These offer superior durability and a finer electrode tip compared to platinum or copper plugs. The extremely hard iridium alloy resists wear, allowing for extended replacement intervals (typically 60,000 miles or more) while maintaining a consistent spark. While copper plugs offer excellent conductivity, their softer electrode wears quickly, requiring much more frequent replacement – usually every 15,000-20,000 miles. Platinum plugs are a step up from copper but still don't match the longevity of iridium.

How to gap a spark plug

For your 2023 Subaru Crosstrek, the factory-recommended spark plugs are pre-gapped and generally should not be adjusted. The fine iridium electrode is delicate and can be easily damaged if you attempt to adjust the gap. Always double-check the part number to ensure you have the correct pre-gapped plug. If, for some reason, you need to verify the gap, use a wire-style spark plug gauge. A feeler gauge style can damage the fine electrode. If the gap is incorrect, it's best to exchange the plug for a properly gapped one rather than attempt to bend the electrode.

Replacement procedure tips

Replacing the spark plugs on your Subaru Crosstrek's horizontally opposed "boxer" engine can be a bit more challenging than on an inline or V-configuration engine due to limited access. The plugs are located on the sides of the engine, requiring some maneuvering.

Coil-on-plug removal: Your Crosstrek uses a coil-on-plug (COP) ignition system, meaning each spark plug has its own ignition coil mounted directly above it. To access the spark plugs, you'll need to carefully disconnect the electrical connector from each coil and then unbolt and remove the coil. Be gentle when pulling on the coil; twisting slightly can help loosen the rubber boot from the spark plug.

Anti-seize debate: There's an ongoing debate about using anti-seize compound on spark plug threads. Most modern spark plugs, especially those from NGK and Denso, have a special coating on the threads that acts as an anti-seize agent. Applying additional anti-seize can actually lead to over-torquing (because the anti-seize lubricates the threads, reducing friction and resulting in a higher clamping force than intended at a given torque spec) or even interfere with the plug's grounding. Subaru (and many spark plug manufacturers) recommends installing plugs dry and torquing them to the specified value.

Dielectric grease on boots: While not for the spark plug threads, a small amount of dielectric grease applied to the inside of the spark plug boot (which connects to the top of the spark plug) can be beneficial. This grease helps prevent moisture intrusion, insulates against voltage leaks, and makes future removal of the coil boot easier.

Known issues

Fortunately, there are no widespread or notorious spark plug-related issues specific to the 2023 Subaru Crosstrek or its FB-series boxer engines, unlike some other manufacturers (e.g., Ford's problematic 2-piece plugs in their 3-valve engines or GM's prior ionization-sensing coil issues). As long as you use the correct OEM or equivalent genuine replacement spark plugs and adhere to the recommended replacement intervals, your Crosstrek's ignition system should provide reliable service.

Need plugs replaced? Find a shop on Repairius.