Parts for your 2013 Subaru Forester-Ignition coils

2013 Subaru Forester ignition coils — what they do and when to replace them

According to Subaru’s factory service information for the 2013 Forester petrol engines (FB25 2.5i and FA20F/XT), the vehicle uses coil-on-plug ignition coils, one per cylinder, as part of its electronic ignition system. Workshop literature for the EE20 2.0D diesel Forester shows no spark plugs or coils, as diesel uses compression ignition. So, ignition coils are fully relevant for 2013 Forester petrol models, but not applicable to the diesel variant.

On petrol 2013 Subaru Foresters, the ignition coil’s job is to take the 12-volt battery feed and step it up to tens of thousands of volts to jump the spark plug gap right when the ECU calls for it. Subaru runs a coil-on-plug setup, so each cylinder gets its own coil for crisp spark delivery and better reliability. When a coil goes weak or fails, the result is usually a misfire under load, rough idle, poor fuel economy, or a flashing check engine light. Common fault codes include P0301–P0304 (misfire) and P0351–P0354 (coil circuit).

There’s no strict replacement interval for coils, they’re replaced on condition. That said, many owners in Australia and New Zealand see original coils last well past 150,000 km, while heat, oil contamination from rocker cover leaks, and age can hasten failure. Any time spark plugs are changed (typically around 100,000 km for iridium plugs), it’s smart to inspect the coils and rubber boots for cracking or arcing marks.

Good servicing habits help coils live longer:

• Fix oil leaks that can soak coil boots.
• Use the correct spec spark plugs and keep the plug gap right.
• Ensure battery voltage and charging system are healthy.
• Keep connectors clean and properly latched, a dab of dielectric grease on boots can help prevent tracking.

Diagnosing a suspect coil is often as simple as a swap test: move the coil from the misfiring cylinder to another and see if the fault code follows. When replacing, quality matters—use reputable OEM-equivalent parts to avoid repeat issues. Replacing one failed coil is fine, but on higher‑kilometre cars many techs recommend doing the set to avoid chasing staggered failures. Always work on a cool engine, disconnect the negative battery terminal, unclip the connector, remove the small retaining bolt, and twist the coil gently before pulling it out. After refitting, clear codes and road test to confirm a smooth, clean pull through the revs.

Popular questions about 2013 Subaru Forester ignition coils

How long do ignition coils typically last on a 2013 Forester?
Many last 150,000–250,000 km or more. Heat, age, and oil contamination are the main coil killers. There’s no scheduled change, replace when symptoms or diagnostics point to a weak or failed unit.

Should all four coils be replaced at once?
It’s acceptable to replace only the failed coil. However, if the vehicle has high kilometres or multiple coils test marginal, replacing the full set can prevent repeat visits. Some owners keep the old working coils as a glovebox spare.

Can driving with a bad coil damage other parts?
Yes. A persistent misfire can overheat and damage the catalytic converter and wash fuel into the oil. If the check engine light flashes, reduce load and sort it promptly.