Parts for your 2014 Subaru Forester-Ignition coils

2014 Subaru Forester ignition coils — what they do and when to replace them

Ignition coils are absolutely fitted to 2014 Subaru Forester petrol models. The Subaru Factory Service Manual for the SJ Forester (2014) and the Subaru parts catalogue both show a coil-on-plug setup for the FB25 2.5i and FA20 2.0i/2.0XT engines. Major ignition component catalogues from OEM suppliers like Denso and NGK also list direct-replacement coils for these petrol variants. Note: the 2.0D diesel Forester doesn’t use ignition coils at all because it relies on compression ignition rather than a spark.

On the petrol Forester, each cylinder gets its own coil-on-plug unit. The job is simple but critical: step up battery voltage and deliver a strong, well-timed spark at the plug so the engine fires cleanly. Coil-on-plug keeps the spark energy right at the plug, reducing losses and improving reliability and emissions. The engine control module manages dwell and firing to suit load, revs and temperature, which is why healthy coils help with smooth idle, decent fuel economy and crisp throttle response.

There’s no fixed service interval for ignition coils in the Subaru schedule, they’re generally replaced on condition. As kilometres rack up, heat and vibration can weaken them. It’s smart to inspect the coil boots when doing spark plugs, look for cracking, carbon tracking or corrosion, and make sure the plug wells are dry and free of oil from rocker cover gasket leaks. If the dash shows a check engine light with misfire or coil circuit codes, or the Forester stumbles under load (especially on turbo 2.0XT models), the coils deserve a look.

• Common signs of a failing coil: rough idle, hard starting, hesitation on hills, poorer fuel use, and a flashing MIL during misfire.

When replacing, use quality OEM-equivalent coils and match part numbers to engine type and VIN. Many owners change only the faulty unit, if coils are the same age and the vehicle has high kilometres, doing the full set can save repeat labour. Fit the new coil firmly onto a correctly gapped, new spark plug, apply a light smear of dielectric grease on the boot, and tighten the retaining bolt to the factory torque in the Subaru manual. Avoid yanking on the connector tab, and always clear codes and road test. If a misfire moves when you swap coils cylinder-to-cylinder, that’s a strong confirmation the coil is the culprit.

FAQs

How often should ignition coils be replaced on a 2014 Forester?
There isn’t a scheduled interval. Many last well beyond 100,000 km. Replace coils when they show symptoms or set diagnostic trouble codes. It’s good practice to inspect them whenever spark plugs are replaced.

Can a bad ignition coil damage the catalytic converter?
Yes. A persistent misfire sends unburnt fuel into the exhaust, which can overheat and damage the catalytic converter. If the MIL is flashing or there’s a confirmed misfire, avoid extended driving and sort the coil or spark issue promptly.

Does the 2014 Forester diesel (2.0D) have ignition coils?
No. The EE20 diesel uses compression ignition and glow plugs for cold starts, so ignition coils aren’t fitted or required on diesel variants.