X4XZ UF303 Ignition Coil & 5019 Double Iridium Spark Plug Kit — 6-Pack for Chevy Trailblazer & GM 2.8L–5.3L, Direct-Fit Reliabilit

X4XZ UF303 ignition coils paired with 5019 double iridium spark plugs replace worn-out components to restore reliable ignition, smoother idling, and steady engine performance for compatible GM vehicles.

This complete kit includes six ignition coil packs and six double iridium spark plugs designed as direct-fit replacements for a range of GM models including Chevy Trailblazer, GMC Envoy, Isuzu Ascender, Buick Rainier, Hummer H3, Oldsmobile Bravada, and Saab 9-7X. Each ignition coil and spark plug combination is engineered to meet or exceed original equipment specifications for fitment and electrical characteristics, simplifying installation while supporting dependable starts, consistent combustion, and reduced misfires.

Which vehicles will these UF303 coils and 5019 plugs fit?

The X4XZ kit targets mid-2000s GM-derived models with 2.8L–5.3L engines. Fitment covers multiple makes and model years; always cross-check your vehicle's VIN or original part numbers before ordering. The package replaces OE numbers like UF303 and commonly matched spark plug codes.

• Chevy: Trailblazer/Trailblazer EXT (2002–2005), Colorado (2004–2006)
• GMC: Envoy/Envoy XL/XUV (2002–2005), Canyon (2004–2006)
• Isuzu: Ascender (2003–2008), I-280/I-290/I-350/I-370 models
• Also compatible: Buick Rainier (2004–2005), Hummer H3 (2006), Oldsmobile Bravada (2002–2004), Saab 9-7X (2005–2009)

How do the double iridium plugs and coils improve ignition reliability?

The spark plugs use a dual iridium construction for a durable, precise firing tip that resists wear and maintains a steady spark over long service intervals. The ignition coils are made from robust materials with internal noise suppression and reinforced connectors to protect against heat and vibration, helping sustain strong spark energy under demanding conditions.

• Double iridium tips extend service life and provide a consistent spark
• Ferrite noise suppressor reduces radio frequency interference
• Thermoplastic coil connectors resist heat-related cracking
• Stainless-steel springs ensure secure, conductive contact

What symptoms will this kit resolve once installed?

Replacing worn coils and plugs often clears common ignition-related drivability issues. Expect improved cold starts, fewer engine misfires, steadier idle, and a smoother throttle response when the components are healthy and correctly installed.

• Reduces or eliminates engine misfire codes
• Improves idle stability and engine smoothness
• Helps restore lost engine power and responsiveness
• Promotes more consistent combustion cycle timing

How straightforward is installation and what’s included?

This kit is built as a direct replacement to match original mounting and electrical connections, making installation quick for most DIYers or professional mechanics. No printed manual is included, but basic steps are standard: disconnect battery, remove old coils and plugs, install new plugs to correct gap and torque, then fit coils and reconnect electrical plugs.

• Included: 6 ignition coil packs + 6 double iridium spark plugs
• OE references: UF303, 12568062, 19300921 and related numbers
• Tools needed: socket set, torque wrench, spark plug socket
• Manufacturer support: 24-hour customer service and 1-year product coverage

Who is this for: Drivers and mechanics working on compatible GM and GM-derived vehicles from the early-to-mid 2000s who want a cost-effective, OEM-equivalent ignition refresh. This kit suits owners experiencing misfires, rough idle, hard starts, or degraded throttle response, as well as vehicle restorers and fleet maintenance teams seeking reliable replacement coils and long-life iridium plugs.