Parts for your 2008 Subaru Forester-Ignition coils

2008 Subaru Forester ignition coils — purpose, care, and when to replace

Ignition coils are absolutely used on the 2008 Subaru Forester. Technical service literature and OEM parts catalogues for the EJ25-powered 2008 Forester (SG/early SH) list ignition coils as standard equipment: many naturally aspirated models run a single “wasted-spark” coil pack that feeds high-tension leads to the plugs, while turbo variants use individual coil-on-plug units on each cylinder. This layout is reflected in Subaru factory service manuals and dealer parts systems for that model year.

On this Forester, the ignition coil’s job is to take the 12-volt battery supply and step it up to the thousands of volts needed to jump the spark plug gap under compression. Strong, well-timed spark means smooth starts, clean idle, decent fuel economy, and lower emissions. When a coil goes weak or fails, the driver will often notice rough running, hesitation, higher fuel use, and a flashing check-engine light with misfire codes (P0301–P0304 or P035x).

Ignition coils aren’t a scheduled “must replace at X km” item, but they do live a hot, vibrating life. As part of routine servicing of a 2008 Subaru Forester, it’s smart to:

• Inspect for cracking, carbon tracking, corrosion, or oil intrusion around the coil or plug wells.
• Check spark plug condition and gap per spec, tired plugs make coils work harder.
• On models with leads, inspect and replace any brittle or high-resistance leads.
• Scan for pending misfire codes after hard, hot drives, early detection saves hassle.

Replacement advice is straightforward. On coil-on-plug turbo models, swap the faulty coil on the affected cylinder, keeping the remaining originals if they test fine. If the vehicle has the single wasted-spark coil pack, replace the pack as a unit when it’s cracked, out of spec, or causing recurrent misfires, always fit quality parts. Clearing corrosion on grounds and connectors helps prevent repeat faults. A light smear of dielectric grease on boots can aid future removal and keep moisture at bay, but don’t drown the terminals.

Most owners will see coils last well past 150,000 km, but age, heat, and plug neglect can bring that forward. If the Forester often tows, tackles beach runs, or sits idling in summer heat, consider proactive testing when doing plugs to head off roadside drama.

Popular questions about 2008 Subaru Forester ignition coils

Does the 2008 Subaru Forester have one coil or four?
Naturally aspirated models commonly use a single wasted-spark coil pack with high-tension leads, while turbo variants have four individual coil-on-plug units. Either way, the system relies on ignition coils, and both types are serviceable parts.

How often should ignition coils be replaced?
There’s no fixed interval. Coils are replaced when testing or symptoms point to a fault—misfires, hard starts, poor economy, or coil-related fault codes. Checking coils when doing spark plugs is a practical approach, especially beyond 150,000 km.

What are the signs of a failing ignition coil on this model?
Tell-tales include rough idle, stumbling under load, higher fuel use, a flashing check-engine light, and codes like P0301–P0304 or P035x. Visual cracks, arcing marks, or corroded connectors are also red flags.