Ignition Coil and Iridium Spark Plugs for Buick Rainier (2004-2005) 4.2L

Direct-Replacement Ignition Kit for 2004-2005 Buick Rainier

What it Does: Replaces degraded factory coil packs and worn spark plugs to eliminate secondary ignition breakdown, misfires, and erratic idle on the 4.2L inline-six platform.

The Stock Rainier Ignition Coil Degradation

The Atlas LL8 inline-six engine relies on coil-on-plug architecture directly seated in deep spark plug wells. Over repeated heat-cycling, OEM epoxy encapsulation degrades, leading to micro-cracks in the coil housings. This causes dielectric breakdown, internal arc-over, and severe misfires under load. Simultaneously, standard copper or worn platinum plugs suffer gap erosion, increasing required secondary voltage and accelerating coil burn-out.

The Engineering Solution

This complete ignition overhaul kit pairs 6 heavy-duty coil packs with 6 fine-wire iridium spark plugs. The ignition coils feature high-conductivity copper primary and secondary windings encased in high-dielectric epoxy to withstand extreme engine bay thermal cycling. The iridium spark plugs offer ultra-high melting points and minimal electrode erosion, requiring less voltage to fire while producing a focused flame kernel for reliable combustion and complete fuel burn.

Technical Specifications

Compatibility

• 2004 Buick Rainier 4.2L L6 (CXL, CXL Plus)
• 2005 Buick Rainier 4.2L L6 (CXL, CXL Plus)
• Interchange: UF303, UF-303, 12568062, 19300921, 8-12568-062-0, 5C1392, E255, IC414, GN10114

The Buick Reliability Standard

Engineered for the demands of midsize SUV towing and daily operation, this ignition kit restores lost fuel economy, sharp throttle response, and smooth idle stability without triggering diagnostic trouble codes.