How long do Subaru Outback spark plugs last?

Most modern Subaru Outbacks use long-life spark plugs that typically last about 100,000 miles under normal driving. Copper plugs, if installed, can wear closer to 60,000 miles.

Lifespan varies by engine type, model year, and how you drive. The exact replacement interval depends on your year and engine, so refer to the Subaru owner's manual or your dealer’s service schedule for precise guidance.

Typical spark plug lifespans by plug type

Here is a quick guide to expected plug life by the common plug materials used in Outbacks.

• Iridium- or platinum-tipped plugs: about 100,000 miles (160,000 km) under normal driving.


• Copper-core plugs: typically about 60,000 miles (96,000 km) and may require earlier replacement—more common on older models.

Always verify with the owner's manual for your exact model year and engine. Weather and driving style can shorten or lengthen the interval.

Engine and model-year variations

While most current Outbacks share a 2.5-liter flat-four engine and use long-life plugs, there have been variations across generations. Details:

• 2.5L FA/FB engines (most 2010s–2020s Outbacks): common replacement interval around 100,000 miles for iridium/platinum plugs.


• 3.6L EZ36 engine (higher trims, earlier generations): similar ~100,000-mile interval, with some service guides noting up to 105,000 miles depending on plug type.


• Older EJ25 engines (pre-2010 Outbacks): plug materials and recommended intervals varied; replacement can range roughly from 60,000 to 100,000 miles depending on the installed plug.

For exact schedules, consult the owner's manual or a Subaru-certified technician.

When to replace spark plugs: symptoms to watch

Recognizing wear early can prevent misfires and fuel-economy losses. Look for these signs:

• Rough idle or engine misfires, especially during acceleration


• Decreased fuel efficiency or loss of engine power


• Difficulty starting or longer cranking times


• Engine knocking or hesitation under load


• Check Engine Light with misfire or ignition-related codes

If you notice these symptoms, have the plugs inspected and replaced as needed. A professional check can also confirm that ignition coils and wires are in good condition.

Tips for replacing and maximizing spark plug life

To extend life and maintain performance, consider these best practices:

• Use the correct plug type and heat range recommended by Subaru for your engine.


• Torque to specification when installing, and verify the gap on replacement plugs.


• Consider replacing ignition coils and spark plug wires at the same time if they show signs of wear or if the vehicle has high mileage.


• Avoid excessive short trips; occasional longer highway drives help keep plugs clean and operating efficiently.


• Keep the fuel and oil systems well maintained, and address oil leaks or fouling promptly to protect plugs.

Following these practices helps ensure the plugs reach the expected interval and deliver consistent performance.

Summary

Across most Subaru Outbacks, spark plugs are designed for long life, typically about 100,000 miles under normal driving conditions. Actual longevity depends on engine type, plug material, driving habits, and maintenance. Always consult the owner's manual for your specific year and engine, and watch for signs of wear that suggest replacement may be due sooner.

How do I know if my Subaru spark plugs are bad?

One of the first signs of spark plug wear is trouble starting your Subaru. If the engine cranks longer than usual before starting or if you experience intermittent starting issues, it's time to inspect your spark plugs.

How much does it cost to replace spark plugs on a Subaru Outback?

The cost to replace Subaru Outback spark plugs typically ranges from approximately $300 to over $800, with prices varying by model, location, and whether you choose a dealership or an independent mechanic. Dealerships generally have higher labor rates and use OEM parts, leading to a higher price, while independent shops may be less expensive. Newer models with more complex engine layouts can sometimes have higher costs, and labor is often the most significant part of the total price.
 
Factors that influence the cost
This video explains what to consider when buying spark plugs: 30sMrSubaru1387YouTube · Jan 9, 2022

• Location and mechanic: Dealerships and independent shops have different pricing structures. Dealerships typically charge more for labor and use official parts, while independent shops can be more affordable. 
• Engine and model year: The specific model and year can impact the cost. Some engine configurations are more labor-intensive, driving up the final price. 
• Parts: The cost of the spark plugs themselves can vary. Genuine Subaru parts are often more expensive than aftermarket options. 
• Labor: Since replacing spark plugs can be a time-consuming job, the labor cost is often the largest portion of the total bill. 

Examples of recent costs (from customer reports)

• $409: Paid at a dealership for a 2020 Outback. 
• $500+: Paid at a dealership for a 2019 Outback. 
• $300: Paid at an independent shop for a 2019 Outback. 
• $225: Paid at a private mechanic for a 2017 Outback. 
• $275: Quoted for a 2018 Outback at an independent shop. 

When to replace spark plugs in Subaru Outback?

The spark plug replacement interval for a Subaru Outback is typically every 60,000 miles, but you should always consult your owner's manual for the specific mileage recommended for your model and engine type. Some models with turbocharged engines may have a slightly different interval, and long-life spark plugs like platinum or iridium can last longer than conventional plugs. 
Key recommendations

• Check your owner's manual: This is the most accurate source for your specific vehicle's recommended maintenance schedule. 
• 60,000 miles is a common interval: This is the standard replacement interval listed in many maintenance schedules for the Outback. 
• Consider your engine type: Models with turbocharged engines may have a slightly different interval than non-turbocharged models. 
• Long-life plugs: If your Outback has platinum or iridium-tipped plugs, they can last significantly longer, potentially 100,000 miles or more. 
• Preventative maintenance: Replacing spark plugs at the recommended interval can prevent future engine issues like misfires and ensure consistent ignition. 

Do I really need to change my spark plugs at 100,000 miles?

Yes, replacing spark plugs at 100,000 miles is a common and often necessary maintenance task, as many modern vehicles have spark plugs rated to last that long. However, the exact interval depends on your vehicle's make, model, and the type of spark plug installed, so you should always check your owner's manual for the manufacturer's specific recommendation. 
This video explains when to change spark plugs and what happens if you don't: 1mHonest Mechanic ColoradoYouTube · Dec 24, 2023
Why it's important

• Engine performance: Spark plugs that are past their prime can cause rough idling, poor acceleration, and decreased fuel efficiency. 
• Preventing damage: Over time, worn-out plugs can put extra stress on other components, like ignition coils, and may seize in the engine block, making them harder to remove later. 
• Preventative maintenance: Replacing spark plugs is a form of preventative maintenance that can prevent more costly repairs down the line. 

This video explains why it's important to change spark plugs at 100k miles: 52sWhite One Auto, LLCYouTube · May 19, 2021
What to consider

• Owner's manual: Your vehicle's owner's manual is the most reliable source for the correct replacement interval and recommended plug type. 
• Spark plug type: The lifespan of spark plugs varies by material. Iridium plugs are often rated for 100,000 miles or more, while other types like copper or platinum have shorter lifespans. 
• Driving conditions: Severe driving conditions can shorten the life of spark plugs, so your interval may be shorter than recommended if you frequently tow, drive in extreme temperatures, or frequently start and stop.