Parts for your 2007 Subaru Impreza-Ignition coils

2007 Subaru Impreza ignition coils — what they do and how to look after them

Ignition coils are absolutely relevant to the 2007 Subaru Impreza. Subaru’s 2007 Factory Service Manual (Engine/IGN section), the Subaru global parts catalogue, and aftermarket application data from NGK/Denso all list ignition coils for this model range. The naturally aspirated 2.5i (EJ253) typically runs a dual-channel coil pack feeding plug leads, while WRX and STI variants use individual coil-on-plug units. Haynes repair coverage for 2001–2007 Impreza backs this layout as well.

Put simply, the coil’s job is to step up the 12‑volt battery supply to the thousands of volts needed to jump the spark plug gap. The ECU commands the coils to fire at precisely the right time so the boxer engine runs smoothly and efficiently. On a 2.5i, the single pack fires pairs of cylinders (a “wasted spark” setup) through leads. On WRX/STI, each cylinder gets its own coil perched directly on the plug for crisp spark control.

Coils aren’t a routine replacement item in the service schedule, but they do appreciate a bit of care. At regular services, a quick visual check for cracks, swelling, carbon tracking, loose connectors, or oil in the plug tubes goes a long way. If it’s a 2.5i, also inspect the high‑tension leads for hardness, arcing marks, or green corrosion at the ends, and make sure they’re routed in the correct order and clipped away from hot or sharp bits. A sparing smear of dielectric grease on boots helps fend off moisture under the bonnet.

When replacement is due, go for OEM‑grade parts (Denso/Hitachi level) and match the correct part number to your VIN. On WRX/STI, it’s fine to replace a single failed coil, though many owners with higher kilometres choose to do the full set for peace of mind. On 2.5i, the coil pack is replaced as an assembly, it’s smart to fit fresh leads and plugs at the same time. Always disconnect the battery, handle the locking tabs gently, and tighten mounts and spark plugs to the Subaru workshop spec.

Typical red flags include a rough idle, misfire under load, flashing check‑engine light, poor fuel economy, and codes like P0301–P0304 or P0351–P0354. If in doubt, a scan-tool misfire counter, a careful resistance check against workshop specs, and a quick swap test between cylinders (for COP) will pinpoint a lazy coil fast.

• Service tip: oil in plug wells from rocker cover leaks can take out coils—fix the leak first.
• Spark plugs on these cars are usually due around 100,000 km (iridium), tired plugs stress coils.

Popular questions

Does a 2007 Subaru Impreza use coil-on-plug or a single coil pack?
For 2007, the 2.5i (EJ253) generally uses a single dual‑channel coil pack with plug leads. WRX and STI turbo models use individual coil‑on‑plug units on each cylinder. Checking the VIN and engine code confirms which setup is fitted.

How often should the ignition coils be replaced?
There’s no fixed interval. Coils are replaced when faulty or when age and heat have clearly taken their toll. Many last well past 150,000 km. Regular inspections and timely spark plug changes help coils live longer.

What are the tell‑tale signs a coil is failing on a 2007 Impreza?
Common clues are hard starts, misfires under load, a rough idle, higher fuel use, and fault codes for misfire or coil circuits. Visual cracks, burn tracks, or oil contamination around the coil or plug wells are also giveaways.