It is imperative that you ensure your spark plugs are in good condition. There’s a likely chance you will need to replace your set of spark plugs several times during your ownership of a 2015 Subaru Impreza. Spark plugs are one of the most important parts inside your engine as they start the entire combustion process that starts and keeps your engine running for many thousands of miles. Similar to most engine parts, spark plugs experience wear over time and eventually need to be swapped out for new replacements, but fortunately this is a repair you can do yourself. Chances are, if you’ve found yourself here, you have no idea how to do that, or perhaps you’d just like to know what kind of spark plugs you need to buy. The entire process of changing your spark plugs should take about 20-45 minutes. This article will go over everything you will need to know about your Subaru Impreza’s spark plugs, whether you need some baseline information or a full, step-by-step guide to performing a spark plug change.
Correct spark plugs on a 2015 Subaru Impreza
CHAMPION 991[/caption]For any 2015 Subaru Impreza, you can use CHAMPION 991 spark plugs. These will be an exact fit and will match the required specifications of your engine. As this 2015 Subaru Impreza features a 4 cylinder engine, ensure you purchase 4 spark plugs. We always try to recommend the best possible spark plugs for the money, and these spark plugs are either a factory recomendation or an equivalent replacement available in today’s market at an affordable price.
How often should I change my spark plugs?
Very generally, it is advised that you replace spark plugs once every 20,000 to 40,000 miles. Of course, please make sure to check your owner’s manual to determine the exact interval determined by Subaru for the 2015 Impreza. Of course, if you drive your vehicle more aggressively or own a Impreza with some modifications, you may want to consider changing your spark plugs closer to the 20,000 miles end of that spectrum.
However, there are also telltale signs of a car that may potentially need a spark plug replacement early, such as:
- Engine misfiring
- Rough idle
- Problems starting your engine
As a quick note, keep in mind that this list is certainly not comprehensive, and these problems on their own do not definitively point to the spark plugs being the standalone culprit. However, the best way to prevent any issues with your vehicle is to take care of it with organized maintenance, and you are definitely doing so with the responsible decision to replace your Subaru Impreza’s spark plugs on a regular basis.
Changing spark plugs on a 2015 Subaru Impreza
This is a process you should be able to do on your own with some standard garage tools. Of course, consult your owner’s manual, as well as a factory service manual (FSM for short) or an equivalent Haynes or Chiltons manual. The video shown below does a good job of outlining the process.
Helpful Tools
- A torque wrench is a vital tool to have in your toolbox. You should check your factory service manual to determine the correct torque rating to use when putting in the new spark plugs for your 2015 Subaru Impreza to be certain they are installed properly.
- A spark plug gap tool. This allows you to check the gap of your spark plugs and modify it if necessary. Most plugs will come pregapped, but if not, you should absolutely have one of these.
- I also highly recommend you have a feeler gauge as it makes it a bit more straightforward to check the exact gap, and it is helpful for countless other jobs.
- A set of spark plug sockets – These come in very handy because many standard sockets are not deep enough for spark plugs. Also, some spark plug holes are a bit smaller, so it requires a thinner wall like the one featured in the product here to fit. The linked product also features a magnet to keep a good hold of the spark plug so you do not drop it into your engine bay!
- A spark plug tester – this is definitely a niche tool, but it can save you a ton of time. Although we’ve discussed spark plug replacement being a good thing to replace regularly and not just when issues occur, you may also be replacing your spark plugs because of an issue. This tool can help you diagnose the definite problem.
Tips for changing spark plugs on your 2015 Subaru Impreza
- Your engine should be cold before you replace your spark plugs. Wait at least 30 minutes after any kind of operation before attempting to replace the spark plugs on your 2015 Subaru Impreza
- First, disconnect the negative terminal of your battery. It is wise to disconnect the battery anytime you work on the electrical system of your Subaru Impreza or any other vehicle.
- You might consider using dielectric grease when installing new spark plugs. You can apply a a little bit to the inside of the boot and the ceramic part of your spark plugs. It prevents voltage leak and helps avoid the misfortune of the boot fusing to the spark plug over time.
- Take this (unofficial advice) lightly as many spark plug manufacturers advise against the use of anti-seize. However, I have heard from numerous old-school mechanics that they always apply a small amount of anti-seize to the threads of their spark plugs, especially on older vehicles.
- One of the most important things to remember is to avoid overtightening the plugs or worse, cracking them due to overtightenting. Use a torque wrench capable of lower, more precise torque ratings to be sure that you don’t make this mistake.