How often do you change spark plugs on a Subaru Impreza?
In most Impreza models, spark plugs are designed to last between 60,000 and 100,000 miles, depending on the plug type and engine. Copper plugs wear faster; platinum or iridium plugs can last far longer.
As Subaru has used several engine families over the years—older EJ-series four-cylinders and the newer FA-series—the exact interval varies by year and model. The best approach is to consult the owner's manual or a dealer, but the guidance below covers common scenarios for recent Impreza models.
What affects the replacement interval
Key factors include the type of spark plug (copper, platinum, or iridium), the engine family your Impreza uses, and driving conditions (frequent short trips, city driving, or high-load operation). The following sections outline typical ranges and what to expect for Impreza models.
Typical replacement intervals by plug type
Plugs are sold in different materials that impact longevity. The list below provides general ranges used by many Subaru owners, though exact intervals depend on your engine and plug brand.
- Copper-core spark plugs: approximately 30,000–60,000 miles. They are cheaper but wear more quickly and often need more frequent changes on older Subaru engines.
- Platinum spark plugs: approximately 60,000–90,000 miles. They offer longer life than copper and are common in many mid-2000s to recent models.
- Iridium spark plugs: approximately 100,000 miles or more. Iridium provides the longest life and is common in current Subaru engines.
In short, the replacement interval is mainly dictated by the plug material and engine; confirm with your model/year's service schedule and the plug specification from Subaru or the plug manufacturer.
Engine family considerations: EJ vs FA
EJ-series and older Impreza engines
Older EJ-series engines (found in earlier Impreza generations) typically used copper or platinum plugs. Expect more frequent changes, often around 60,000 miles for platinum or copper within 30,000–60,000 miles depending on plug type and maintenance history. For these engines, many owners schedule plug changes every 60,000 miles as a rule of thumb, especially with 2.0–2.5L variants.
FA-series engines and modern Impreza models
Newer FA-series engines (2.0L and 2.4L in more recent Impreza models) are designed for longer-life iridium or platinum plugs. The recommended interval commonly lands around 100,000 miles in many 2012–present Impreza configurations, though some brands may specify a slightly higher or lower interval depending on the exact plug. Always verify against the official maintenance schedule for your specific year and engine code.
Signs you should inspect or replace plugs sooner
Regardless of the official interval, you should consider inspecting or replacing spark plugs if you notice the following symptoms, which can indicate worn or fouled plugs.
- Rough idle or misfire, especially on startup or under load
- Reduced engine performance or acceleration
- Decreased fuel efficiency or higher fuel costs
- Check Engine Light with misfire or misfire-related codes
- Difficulty starting or extended cranking time
In any of these cases, a diagnostic check and spark plug inspection are warranted, and you should consult a mechanic or perform a replacement if needed.
DIY vs professional service
Replacing spark plugs can be a manageable DIY job for many drivers, especially on four-cylinder engines. However, access and torque specifications vary by engine and may require special tools. If you’re comfortable with basic hand tools and following a service manual, you can save on labor costs; otherwise, a professional shop can ensure correct torque, gapping, and ignition coil health. Always replace the ignition coils if they show signs of wear or damage.
What to expect during a service appointment
Typical service will include removal of ignition coils, inspecting coils and boots, cleaning the area, replacing the plugs with the specified type, and re-torquing to Subaru's specs. Expect a service bill that reflects labor plus parts; in many regions, a four-plug replacement ranges from modest DIY cost to several hundred dollars at a shop, depending on the vehicle year and the shop's rates.
Bottom line for Impreza owners
Always check the owner's manual or Subaru's official maintenance schedule for your exact year and engine code. If you have iridium or platinum plugs, expect a replacement interval near 100,000 miles; for copper plugs, plan on around 30,000–60,000 miles. If you drive in harsh conditions or frequently use short trips, you may need to replace sooner. Regular inspection during routine maintenance will help you catch wear before it affects performance.
Summary
Spark plug replacement intervals for the Subaru Impreza vary mainly by plug material and engine family. Copper plugs require more frequent changes (roughly 30k–60k miles), while platinum and especially iridium plugs can last around 60k–100k miles or more. Always consult the specific service schedule for your vehicle and consider driving conditions. Regular checks ensure smooth performance and reliability for the Impreza lineup.
