How to Change Spark Plugs on Subaru: Expert Tips

Spark plugs are a crucial component of your Subaru’s engine. Over time, they can become worn out and less effective, leading to issues with starting the car, rough idling, and decreased fuel efficiency. Fortunately, changing the spark plugs on a Subaru is a relatively straightforward task that can be performed with just a few basic tools and some patience. In this guide, we’ll walk you through the step-by-step process of changing the spark plugs on your Subaru, helping you keep your engine running smoothly and efficiently.

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1. Gather the Necessary Tools and Materials

Before getting started, you’ll need to gather the following tools and materials:

Tools Materials
  • Ratchet wrench
  • Spark plug socket
  • Socket extension
  • Gap gauge tool
  • Torque wrench
  • Anti-seize lubricant
  • Dielectric grease
  • New spark plugs
  • Clean cloth

2. Locate the Spark Plugs

The spark plugs in a Subaru are typically located on the top of the engine, with one spark plug per cylinder. You may need to remove a plastic engine cover to access the spark plugs. Refer to your Subaru’s owner’s manual for the specific location of the spark plugs in your vehicle.

3. Remove the Old Spark Plugs

Once you’ve located the spark plugs, follow these steps to remove the old spark plugs:

  1. Ensure the engine is cool to the touch.
  2. Disconnect the spark plug wires or ignition coils from the spark plugs.
  3. Use the ratchet wrench, spark plug socket, and socket extension to gently loosen and remove each spark plug from the engine.
  4. Inspect the old spark plugs for signs of wear, such as fouling or excessive corrosion.

4. Prepare the New Spark Plugs

Before installing the new spark plugs, it’s important to properly prepare them:

  1. Check the gap of each new spark plug using the gap gauge tool, and adjust the gap as needed to match your Subaru’s specifications.
  2. Apply a small amount of anti-seize lubricant to the threads of each new spark plug to prevent them from seizing in the engine.

5. Install the New Spark Plugs

Once the new spark plugs are prepared, carefully install them by following these steps:

  1. Thread each new spark plug into the engine by hand to avoid cross-threading.
  2. Use the torque wrench to tighten each spark plug to the manufacturer’s specified torque setting, ensuring a snug fit without over-tightening.
  3. Reconnect the spark plug wires or ignition coils to the new spark plugs.

6. Apply Dielectric Grease (Optional)

Applying a small amount of dielectric grease to the inside of the spark plug wire boots or the top of the ignition coil can help prevent moisture and corrosion, ensuring a solid electrical connection.

7. Reassemble and Test

Finally, reassemble any components you removed to access the spark plugs, and start the engine to ensure it runs smoothly with the new spark plugs installed. Take your Subaru for a test drive to verify that the engine operates correctly and that any previous issues have been resolved.

Frequently Asked Questions Of How To Change Spark Plugs On Subaru: Expert Tips

How Often Should Spark Plugs Be Changed On A Subaru?

Ideally, spark plugs should be replaced every 30,000 miles or as per the manufacturer’s recommendation for optimal engine performance.

What Are The Signs Of Worn-out Spark Plugs In A Subaru?

Common signs include rough idling, poor acceleration, decreased fuel efficiency, and engine misfires. Regular inspection is crucial.

Can I Change Spark Plugs On My Subaru At Home?

Yes, changing spark plugs on a Subaru can be done at home with basic tools and proper guidance. It’s a fairly straightforward process.

Is It Essential To Use Oem Spark Plugs For A Subaru?

Using OEM or recommended spark plugs is crucial for ensuring compatibility and optimal performance of the Subaru’s engine. Always follow manufacturer guidelines.


Changing the spark plugs on your Subaru is a relatively simple maintenance task that can have a significant impact on the performance and efficiency of your vehicle. By following the steps outlined in this guide and using the right tools and materials, you can ensure that your Subaru’s engine continues to run smoothly and reliably for years to come.

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