Parts for your 2006 Subaru Impreza-Ignition coils

2006 Subaru Impreza ignition coils

According to the Subaru Factory Service Manual for the 2006 Impreza (Ignition System section), Subaru’s Technical Information System (STIS), and the genuine Subaru parts catalogue, every 2006 Impreza variant is fitted with ignition coils. Naturally aspirated models typically run a single wasted-spark coil pack with high-tension leads, while WRX and STi turbo models use individual coil-on-plug (COP) units at each cylinder. So yes—ignition coils are absolutely relevant on a 2006 Subaru Impreza.

Ignition coils take the battery’s low voltage and step it up to the tens of thousands of volts needed to fire the spark plugs. Whether it’s the NA coil pack sending spark down leads or the WRX/STi’s COP units firing directly on the plugs, healthy coils are vital for smooth starts, crisp acceleration, good fuel economy, and clean emissions.

Coils aren’t a scheduled replacement item, but they deserve attention during routine servicing. On NA models, inspecting the coil pack and leads at regular service intervals helps catch early signs of trouble like cracking, carbon tracking, or swollen, oil-soaked insulation. For WRX/STi COP setups, check for cracked housings, brittle connectors, and moisture or corrosion around the plug tubes. Dielectric grease on boots and clean, snug electrical connections go a long way to keeping misfires at bay.

• Common symptoms of a tired coil include rough idle, hesitation under load, higher fuel use, and stored misfire codes (P0301–P0304). A flashing MIL under load is a red flag.
• If replacing plugs, it’s smart to assess coil health at the same time. Any coil showing heat stress, cracks, or green/white corrosion should be replaced.
• Use quality parts that match the engine variant. NA coil packs and WRX/STi COP units are not interchangeable.

When fitting coils, disconnect the battery, avoid yanking on leads, and keep the plug tubes clean so grit doesn’t fall onto threads. Lightly seat boots, ensure connectors click home, and route leads on NA models exactly as per the factory path to avoid crossfire. A scan tool road test after the job helps confirm no fresh misfire counts. With solid coils and fresh plugs, the EJ engine feels smoother, pulls harder, and sips less fuel—too easy.

Popular questions

Do the 2006 Impreza NA and WRX use the same ignition coils?
Not usually. The naturally aspirated 2006 Impreza commonly uses a single wasted-spark coil pack with leads, while WRX and STi engines use individual coil-on-plug units. The mounting, connectors, and operation differ, so parts aren’t interchangeable. Checking the VIN and engine code against a Subaru parts catalogue is the safe move.

How long do ignition coils last on a 2006 Impreza?
There’s no fixed interval. Many last well past 150,000 km, but heat, oil intrusion, and age can shorten their life. If the car shows misfires, rough idle, or poor economy—and plugs and leads (where fitted) are good—testing coils with a scan tool and basic resistance checks is wise.

Should coils be replaced when changing spark plugs?
Not by default. Coils can be re-used if they test fine and show no damage. That said, if access is tight (COP on turbo models) and a coil looks suspect—cracked boot, corrosion, or intermittent misfire—replacing it during the plug job can save doing the work twice.