Parts for your 2009 Subaru Forester-Ignition coils

2009 Subaru Forester ignition coils: purpose, care and when to replace

Based on technical references including the Subaru Forester (SH) factory service manual (EJ25 Ignition System), Subaru parts catalogues, and Denso/NGK ignition application guides, the 2009 Subaru Forester petrol models (EJ253/EJ255) are fitted with individual coil-on-plug ignition coils. These coils are essential for spark ignition. The EE20 2.0D diesel Forester offered in some AU/NZ markets does not use ignition coils, as it’s a compression-ignition engine that relies on glow plugs instead.

On petrol 2009 Foresters, each cylinder gets its own coil mounted directly on the spark plug. The coil’s job is to take 12 volts and step it up to the thousands needed to fire the plug cleanly under load. Coil-on-plug improves spark energy, reduces lead losses, and helps with smoother starts, better fuel economy and lower emissions when everything’s healthy.

There’s no strict service interval for coils, but they live in a hot spot and can age with heat, vibration and moisture. Most workshops in Australia and New Zealand check coil condition whenever spark plugs are due (often around 100,000 km on many plug types) or any time there’s a misfire. If one coil fails, it’s fine to replace just the faulty unit, though on higher‑kilometre vehicles some owners choose to do pairs or a full set for peace of mind.

• Common signs a coil is on the way out: rough idle, hesitation under load, poor fuel economy, hard starts, and a glowing Check Engine Light. Scan tools often show misfire codes (P0301–P0304) or coil circuit faults (P0351–P0354).
• Handy care tips: keep water and degreaser away from the tops of the coils when washing the engine bay, ensure the coil boots are clean and dry, use a dab of dielectric grease on the plug insulator, and torque the plugs correctly so the coil seals properly on the cam cover.
• When replacing, stick with quality OEM-spec coils and confirm the correct part for EJ253 vs EJ255. After fitting, clear codes and road test under load to confirm the misfire’s gone.

Popular questions

How often should the ignition coils be replaced on a 2009 Subaru Forester?
There’s no fixed interval. Coils are replaced on condition—typically when a misfire code appears or performance drops. Many techs inspect coils whenever spark plugs are renewed (around the 100,000 km mark, depending on plug type) and during any drivability diagnosis.

What are the common symptoms of a failing ignition coil on this model?
Expect a rough idle, stumble under acceleration, sluggish performance, increased fuel use, and a Check Engine Light. Diagnostic codes often show cylinder‑specific misfires (P0301–P0304) or coil circuit faults (P0351–P0354).

Do diesel 2009 Foresters have ignition coils?
No. The 2.0D EE20 diesel is a compression‑ignition engine and uses glow plugs, not ignition coils. The coil-on-plug info here applies to petrol EJ25 models only.