Parts for your 2020 Subaru Legacy-Spark plugs

2020 Subaru Legacy spark plugs — what they do and when to replace them

Spark plugs are absolutely relevant to a 2020 Subaru Legacy. The model runs petrol, spark‑ignition boxer engines (the 2.5‑litre FB25 or the 2.4‑litre FA24 turbo), so plugs are a scheduled service item. Technical references that confirm this include the 2020 Subaru Legacy Owner’s Manual and the Subaru Warranty & Maintenance Booklet, plus NGK and Denso application catalogues that list OEM‑spec iridium plugs for both engines.

In this Legacy, each plug lights the air‑fuel mix precisely when the engine control unit calls for it. That clean, consistent spark keeps the boxer running smooth, helps fuel economy, and protects the catalytic converters by ensuring combustion is completed in the chamber rather than the exhaust. Modern iridium plugs also cope well with the hotter, leaner conditions of direct injection, which both engines use.

For servicing, stick to Subaru’s schedule in the Warranty & Maintenance Booklet. Many markets specify around 96,000 km (60,000 miles) for the FA24 turbo. The FB25 2.5‑litre can differ by market and fuel quality, workshops commonly see intervals between 96,000 and 160,000 km. Given Aussie and Kiwi conditions (heat, urban trips, occasional towing), it’s smart to have the plugs inspected around every 30,000–50,000 km or 2–3 years, with earlier checks if cold starts, short runs, or rough idle crop up.

• Signs they’re due: harder starts, misfires under load, rough idle, drop in fuel economy, sluggish acceleration, or a flashing MIL.
• Fitment tips: use OEM‑spec iridium plugs matched to engine code and VIN, they’re typically pre‑gapped for this application.
• Don’t add anti‑seize to modern plated plugs, it alters torque. Always torque to the Subaru service manual spec on a cool engine.
• Inspect coil boots and connectors, replace any heat‑hardened or cracked bits to avoid future misfires.

The boxer layout can make access tight, but with the right tools and procedure a trained tech will swap all four quickly and correctly. Keeping fresh, correctly torqued plugs in the 2020 Legacy pays back in smooth idle, crisp throttle response, reliable cold starts, and lower emissions—nice wins for everyday driving across Australia and New Zealand.

Popular questions about 2020 Subaru Legacy spark plugs

Does the 2020 Subaru Legacy use spark plugs?
Yes. Both available 2020 Legacy petrol engines—the 2.5L FB25 and the 2.4L FA24 turbo—use spark plugs. Subaru’s 2020 Legacy Owner’s Manual and the Warranty & Maintenance Booklet list spark plugs as a scheduled service item, and NGK/Denso catalogues list specific iridium plugs for these engines.

How often should the spark plugs be replaced?
Follow the Subaru Warranty & Maintenance Booklet for your market. The FA24 turbo is typically 96,000 km (60,000 miles). The FB25 interval varies by region and usage—often between 96,000 and 160,000 km. If the car does frequent short trips or idling, have them inspected earlier.

What plug type should be fitted?
Use OEM‑equivalent iridium long‑life plugs from reputable brands (e.g., NGK or Denso) specified for the engine code and VIN. They come pre‑gapped for the application, don’t file the electrodes. Fit to the correct torque on a cool engine and avoid anti‑seize on plated plugs.