Parts for your 2012 Subaru Legacy-Ignition coils

2012 Subaru Legacy ignition coils

Based on the Subaru Factory Service Manual for the 2012 Legacy/Outback (BR/BM) and the Subaru global parts catalogue, the 2012 Subaru Legacy (sold as Liberty in Australia) is fitted with individual coil-on-plug ignition coils on all petrol engines, including the 2.5i FB25 and 3.6R EZ36. There’s no distributor or remote “coil pack” on this model, each cylinder gets its own coil mounted directly on the spark plug.

Those ignition coils take the vehicle’s 12-volt supply and step it up to the high voltage needed to jump the spark plug gap, lighting the air–fuel mix with precise timing from the ECU. With a coil sitting right on each plug, spark energy is strong and consistent, cold starts are cleaner, and emissions stay in check. It’s a tidy, reliable setup when kept in good nick.

Coils aren’t a scheduled replacement item, but they do live a hard life—heat, vibration and moisture can wear them out. As part of routine servicing on a 2012 Legacy/Liberty, it’s smart to:

• Inspect coil connectors and wiring for looseness, corrosion or heat damage.
• Check for oil in the plug tubes (rocker cover gasket seepage can foul coils and boots).
• Listen/feel for misfires under load and scan for fault codes like P0301–P0304 or P0351–P0354.
• Replace spark plugs at the recommended interval, tired plugs make coils work harder.

Common symptoms of a failing coil include a rough idle, hesitation on hills, worse fuel economy and a flashing check engine light under load. A quick at-home check is to swap the suspect coil to another cylinder—if the misfire code follows, that coil’s likely the culprit. When replacing, quality matters: choose genuine Subaru or reputable aftermarket coils to avoid drivability dramas. Coils can be replaced one at a time, though at higher kilometres some owners opt to do the full set for peace of mind.

During installation, keep the plug well clean, use a light smear of dielectric grease on the boot, seat the coil squarely on the plug, and tighten the small mounting bolt only to the manufacturer’s spec—overtightening can crack the housing. Avoid pressure-washing the engine bay, water ingress is a coil killer. Look after the ignition coils and the FB25/EZ36 engines reward with smooth, efficient running across Aussie and Kiwi conditions.

Popular questions about 2012 Subaru Legacy ignition coils

How long do the ignition coils usually last?

Many 2012 Legacy/Liberty coils run well past 150,000–200,000 km, but lifespan depends on heat, plug condition and moisture exposure. They’re replaced on condition—monitor for misfires and scan for codes during regular services.

Should all coils be replaced at once?

It’s fine to replace a single failed coil. If the vehicle has high kilometres and multiple coils show intermittent faults, doing the full set can save repeat labour and keep performance consistent.

Is it safe to drive with a faulty ignition coil?

Best to avoid it. A persistent misfire can overheat and damage the catalytic converter and may leave the driver stranded. If the check engine light is flashing, reduce load and have it checked promptly.