Parts for your 2018 Subaru Impreza-Ignition coils

2018 Subaru Impreza ignition coils

Based on Subaru’s 2018MY Impreza service manual (Engine/IGNITION section), the car runs a direct, coil-on-plug setup with an individual ignition coil for each cylinder. Subaru’s genuine parts catalogue lists an ignition coil assembly for the 2018 Impreza (GK/GT), and Subaru technical service information notes design updates to these coils on 2017–2019 models. So yes—ignition coils are absolutely fitted and relevant on the 2018 Subaru Impreza.

The ignition coils on a 2018 Impreza take the 12-volt battery feed and step it up to the high voltage needed to fire the spark plugs. With the FB-series 2.0-litre engine, each cylinder gets its own coil perched right on the plug, which means cleaner spark control, better efficiency, and fewer leads to age or crack. When the coils are healthy, the Impreza starts crisply, idles smoothly, and sips fuel the way it should on the daily commute or a weekend run over the ranges.

Coils aren’t a scheduled replacement item like engine oil or filters. Instead, they’re replaced when they show signs of wear or fault. As part of routine servicing—especially around major services where the spark plugs are due (often near the 100,000 km mark, depending on market and conditions)—it’s smart to check the coils and their boots for cracking, carbon tracking, moisture intrusion, or loose connectors. Keeping the plug wells clean and dry, and using quality iridium plugs at the correct gap, helps the coils live a long and happy life.

• Common signs a coil may be failing:
  • Rough idle, hesitation, or a flat spot under load
  • Check Engine Light with misfire codes (P0300–P0304)
  • Poor fuel economy or a raw-fuel smell from the exhaust

When replacement’s needed, quality matters. Using the latest-spec genuine or reputable-brand coils that meet Subaru’s updated design helps avoid repeat misfires. Many techs will replace just the faulty unit, on higher-kilometre cars, doing the full set can save a return trip. Always seat the coil squarely on the spark plug, ensure the connector clicks home, and avoid yanking on the wiring. A light smear of dielectric grease on the inside of the boot (not on the electrode) can help prevent moisture creep, which is handy in wet Kiwi and Aussie conditions.

Look after the ignition coils and the Impreza rewards with smooth starts, tidy throttle response, and fewer dramas at WOF or rego time.

Popular questions

How many ignition coils does a 2018 Subaru Impreza have?
It has four—one coil per cylinder in a coil-on-plug layout. This individual setup improves spark accuracy and reliability compared with older single-coil or remote pack systems.

When should the ignition coils be replaced?
They’re not a routine replacement item. Replace a coil when there are misfire symptoms or fault codes, or if inspection shows damage or moisture tracking. It’s a good idea to inspect them whenever spark plugs are serviced, typically around major service intervals.

Can a failing coil damage the catalytic converter?
Yes, if left misfiring for long. Unburnt fuel can overheat and harm the catalyst. If the Check Engine Light flashes or there’s a persistent misfire, get it checked promptly to protect the exhaust system.