Ignition Coil and Iridium Spark Plugs for Subaru Legacy (2013-2018) 2.5L

Direct-Fit High-Dielectric Ignition Kit for 2013-2018 Subaru Legacy

Primary Function: Complete drop-in ignition refresh engineered to restore primary spark energy, eliminate secondary voltage leakage, and stabilize idle across all four combustion chambers.

The Stock Legacy Ignition Thermal Breakdown

The horizontally opposed layout of the Subaru FB25 boxer engine positions ignition coils in close proximity to the cylinder head exhaust runners and chassis frame rails. Prolonged exposure to extreme heat cycles causes OEM coil potting epoxy to degrade and internal copper windings to experience thermal fatigue. Over time, this leads to micro-arcing, intermittent high-load misfires (DTC P0301–P0304), sluggish throttle response, and incomplete fuel combustion.

The Engineering Solution

This comprehensive kit replaces fatigued factory components with four high-insulation coil-on-plug assemblies and matched iridium spark plugs. The ignition coils feature dense, premium-grade internal copper windings and high-dielectric epoxy potting that resist thermal breakdown under sustained operational temperatures. Paired with fine-wire iridium center-electrode plugs, this setup reduces required ignition voltage, prevents electrode quenching, and guarantees a crisp, consistent flame front initiation.

Technical Specifications

Compatibility

• 2013-2014 Subaru Legacy 2.5i, Premium, Limited (BM Chassis / 2.5L FB25 H4)
• 2015-2018 Subaru Legacy 2.5i, Premium, Sport, Limited (BN Chassis / 2.5L FB25 H4)

The Subaru Boxer Standard

Engineered to withstand the demanding horizontal geometry and thermal footprint of Symmetrical AWD platforms, this ignition system delivers reliable cold-weather starting, linear torque delivery, and zero check-engine lights.