Parts for your 2015 Subaru Outback-Ignition coils

2015 Subaru Outback ignition coils — what they do and when to replace

Technical references confirm that ignition coils are fitted to petrol 2015 Subaru Outback models and not used on the diesel. The Subaru Factory Service Manual (2015 Legacy/Outback), Subaru Global Parts Catalogue, and NGK/Denso application guides show coil‑on‑plug units on the FB25 2.5i (four coils) and EZ36 3.6R (six coils). The 2.0D EE20 turbodiesel uses compression ignition, so it doesn’t have or need ignition coils.

For petrol variants, the ignition coils are the unsung heroes that take the battery’s 12 volts and step it up to the tens of thousands needed to jump the spark plug gap. On the 2015 Outback they’re coil‑on‑plug units, sitting right on each plug for a strong, precise spark commanded by the engine computer. When they’re healthy, the Outback starts crisply, idles smoothly, pulls cleanly up hills, and sips fuel the way Subaru intended.

Owners typically first notice a failing coil as an intermittent misfire under load, a rough idle, or a sudden loss of power. The check engine light often logs codes such as P030X (misfire on a specific cylinder) or P0351–P0356 (ignition coil circuit). Left alone, persistent misfire can overheat the catalytic converter and waste fuel.

• Rough idle, hesitation, or surging under load
• Hard starting or poor fuel economy
• Check engine light with misfire/coil circuit codes
• Raw fuel smell from the exhaust during a heavy misfire

Ignition coils aren’t a routine replacement item, but they appreciate a bit of care. During scheduled spark plug changes (around the 100,000 km mark, model and market dependent), it’s smart to inspect each coil and boot for cracking, oil contamination from rocker cover leaks, or moisture tracks. Keep the plug wells clean, use a dab of dielectric grease on the boots, and avoid yanking on connectors or leads. Heat is the enemy, so any cooling or oil leak that bakes the wells should be sorted promptly.

When replacement is needed, swap the suspect coil with the correct part number for the engine (FB25 vs EZ36 differ) and consider fresh iridium plugs at the same time. Coils usually fail one at a time, but higher‑mileage vehicles may benefit from replacing them in pairs on the same bank. Fit the new coil squarely on the plug, tighten the mounting bolt snugly, reconnect the harness till it clicks, clear the fault codes, and road‑test. A smooth idle and clean pull through the revs means the job’s a good one.

How long do ignition coils last on a 2015 Outback?

Many go well past 150,000–200,000 km. Heat, oil in the plug wells, and worn spark plugs can shorten their life. Regular plug changes and fixing rocker cover leaks help coils live longer.

Can the vehicle be driven with a bad ignition coil?

It’ll usually run, but it’s not a great idea. A steady misfire can overheat the catalytic converter and burn more fuel. Best to minimise driving and sort the faulty coil promptly.

Are coils interchangeable between the 2.5i and 3.6R?

No. The FB25 and EZ36 use different coil part numbers, and the diesel 2.0D uses none. Always match by VIN/engine code to avoid fitment dramas.