Parts for your 2010 Subaru Outback-Ignition coils

2010 Subaru Outback ignition coils — what’s fitted and how to look after them

Based on the Subaru Factory Service Manual for the BM/BR series, Subaru Technical Information System (STIS), and OEM parts catalogues for the 2010 model year, ignition coils are fitted to the petrol-powered 2010 Subaru Outback (2.5i EJ25 four-cylinder and 3.6R EZ36 six-cylinder), using coil-on-plug units. The diesel 2.0D (EE20) variant does not use ignition coils, as it relies on compression ignition rather than spark ignition. These references confirm coils are relevant for petrol trims and not applicable to the diesel.

• Subaru Factory Service Manual (BM/BR Outback/Liberty), Engine sections: EJ25 and EZ36
• Subaru Technical Information System (STIS) parts and wiring diagrams
• OEM and aftermarket parts catalogues for 2010 Outback ignition components
• EE20 diesel engine manual (notes compression ignition, no spark or coils)

For the 2.5i and 3.6R, the ignition coils are the unsung heroes of smooth, efficient running. Each coil sits directly on top of a spark plug, transforming the battery’s 12 volts into the high-voltage punch needed to ignite the fuel-air mix. Good coils mean crisp starts, steady idle, solid fuel economy and proper power under load — just what a Kiwi or Aussie owner expects from a well-kept Outback.

As part of regular servicing, coils don’t have a fixed replacement interval, but they should be inspected whenever spark plugs are changed (typically around 100,000 km for iridium plugs) or if there’s a misfire code. On Subaru’s boxer engines, it’s smart to check for oil in the plug tubes — a common rocker cover gasket weep can soak boots and shorten coil life. Keep boots clean and dry, use a dab of dielectric grease on reassembly, and avoid pulling on the wiring when removing coils under the bonnet.

Common signs a coil is on the way out include a rough idle, hesitation under load, higher fuel use, and a check engine light with misfire codes (often P0301–P0306 depending on cylinder). If one coil fails on a high-kilometre Outback, many workshops recommend testing the set, replacing coils in pairs or as a full set can save repeat visits, especially on the EZ36 with six units tucked along each bank.

When replacing, stick with quality OEM-spec coils to ensure correct dwell and spark energy. Confirm the coil-on-plug layout for the specific engine (EJ25 has four coils, EZ36 has six), disconnect the battery before unplugging connectors, and torque fasteners snugly without overdoing it. A quick post-replacement scan to clear codes and verify no new faults is the tidy way to finish the job.

Note for diesel owners: The 2010 Outback 2.0D uses compression ignition and glow plugs, not ignition coils. If it’s a diesel, coils aren’t fitted or required.

Popular questions about 2010 Subaru Outback ignition coils

Do all 2010 Outbacks have ignition coils?
Petrol models (2.5i and 3.6R) do — they use individual coil-on-plug units. The 2.0D diesel does not, because it doesn’t use spark ignition. If unsure which you have, check the build plate or engine code under the bonnet.

How often should the coils be replaced?
There’s no set interval. Coils are typically replaced only when they show symptoms or trigger misfire codes. Inspect them whenever spark plugs are changed and if there’s oil in the plug tubes, address the leak to protect the coils.

What are the signs of a failing coil on a 2010 Outback?
Look for rough idle, stumbling on hills, increased fuel use, hard starts, and a check engine light with cylinder-specific misfire codes. On high-kilometre vehicles, testing all coils is a good shout to avoid chasing intermittent faults.