Parts for your 2020 Subaru Impreza-Ignition coils

2020 Subaru Impreza Ignition Coils

Ignition coils are absolutely relevant to the 2020 Subaru Impreza. Technical sources including Subaru’s service documentation (STIS: FB20 Engine – Ignition System) specify a coil-on-plug setup with four individual coils, one per cylinder. Subaru genuine parts catalogues and major aftermarket catalogues from DENSO and NGK also list direct-fit ignition coils for the 2020 Impreza, confirming the part’s presence and serviceability on this model.

On the 2020 Impreza’s FB20 petrol engine, the coil-on-plug units transform the 12-volt supply into the high voltage needed to fire the iridium spark plugs under all loads. That crisp spark keeps combustion tidy, fuel economy stable and emissions in check. If a coil gets lazy, the Impreza can develop a rough idle, sluggish take-off, higher fuel use and a flashing MIL with misfire codes (often P0301–P0304).

There’s no fixed replacement interval for ignition coils, they’re replaced on condition. During routine servicing—especially when the spark plugs are due (around the 100,000 km mark, depending on local schedule)—a tech will usually:

• Inspect coil boots for cracking, tracking marks and oil contamination from rocker cover leaks
• Check connectors and loom for corrosion or loose pins
• Scan for stored or pending misfire codes and review misfire counters
• Verify secondary insulation integrity and consistent spark performance under load

If one coil fails, it’s common to replace just the faulty unit. However, on higher-kilometre cars, replacing coils in pairs or all four can reduce future downtime. Always refit with quality coils that match OE spec, ensure spark plug wells are dry and clean, and apply a light smear of dielectric grease to the inside of the boot to help sealing and future removal. Coil hold-down fasteners should be tightened to factory spec and plugs torqued correctly to avoid heat cycling and micro-movement that can shorten coil life.

City driving, heat, and moisture under the bonnet are the usual coil killers. Keeping the engine covers ventilated, addressing oil seepage early, and sticking with the correct heat range plugs helps coils live a long, quiet life. When the Impreza’s coils are healthy, cold starts are easy, throttle response is snappy, and the boxer hum stays smooth—exactly how owners in Australia and New Zealand like it.

Popular questions about 2020 Subaru Impreza ignition coils

How long do ignition coils last on a 2020 Impreza?
Most last well beyond 100,000 km, especially with good plugs and no oil in the plug tubes. They’re not a scheduled item—replace when symptoms or diagnostics point to a weak or failed coil.

Can the car be driven with a failing coil?
It will usually run, but it’s not a great idea. Misfires can damage the catalytic converter and wash cylinder walls. If the MIL is flashing or there’s a persistent stumble, it’s best to sort it promptly.

Are coils interchangeable between cylinders?
Yes, for diagnosis. Swapping a suspect coil to another cylinder is a quick way to see if the misfire follows the coil. For permanent replacement, fit a correct-spec new coil and clear codes.