Ignition Coil Pack UF303 and Iridium Spark Plugs 5019 - Engine Restore

In this review of the Ignition Coil Pack UF303 paired with Iridium Spark Plugs 5019, the bottom line is simple: this set is aimed at owners of compatible Buick, Chevy, GMC, Hummer, Isuzu, Oldsmobile and Saab V6/L4/L5/L6 vehicles who need a cost-effective ignition refresh to cure misfires and sluggish starts. The single biggest reason to buy is the combined replacement approach - new coil packs and iridium plugs together address both ignition and electrode wear so the engine often feels noticeably smoother after installation. OE cross checks are required before purchase.

Key Features

• Vehicle compatibility: Fits a wide range of GM and related models so owners of Rainier, Trailblazer, Canyon, Envoy and H3 can find a direct fit when OE numbers match.
• Coil construction: Coil packs use silicon steel, Japan-imported rubber and Germany-imported varnished wire for improved durability and longer service life.
• Spark plug design: Iridium electrode and advanced ceramic promise quicker starts and steadier acceleration compared with worn factory plugs.
• Complete set: Sold as sets of six, providing a full ignition refresh that addresses misfires and uneven idle when multiple cylinders show wear.
• OE cross references: Multiple reference numbers listed for both UF303 and 5019 make it easier to confirm fitment against existing parts.

Who It's For

This kit is best for DIY mechanics and independent repair shops working on mid-2000s GM-based SUVs and trucks who want to replace both ignition coils and plugs at once to restore engine smoothness and reduce fuel use. It also suits owners who have covered over 80,000 km and are experiencing shaking, hard starting, misfires or slow acceleration.

It is not ideal for buyers who cannot verify OE compatibility from the vehicle or part images, or for those who require dealer-branded OEM items; some customers reported fit variation and occasional corrosion on older replacement coils, so confirm fitment and inspect for warranty options if corrosion resistance is a top priority.

Pros & Cons

Pros

• Improves engine performance and cures misfires when fitment is correct.
• Good value for money as a combined coil and plug package that saves separate purchases.
• Iridium spark plugs deliver reliable ignition and quicker starts compared with worn plugs.

Cons

• Fitment is vehicle-specific and some buyers reported that parts did not match their application, so OE checking is essential.
• There are occasional reports of corrosion or early coil failure on some used-vehicle installs, so longevity may vary by environment.

Specifications

Our Verdict

For owners who can verify OE numbers and need to cure misfires or restore responsiveness on compatible GM-based vehicles, this UF303 coil and 5019 iridium plug set is a cost-effective way to breathe new life into an older engine. It pairs durable coil construction with premium iridium plugs for solid performance and overall value, but buyers should confirm fitment and be aware of isolated corrosion reports.

Frequently Asked Questions

Will these parts fit my vehicle?
Check the OE cross-reference numbers and the vehicle fitment photos or detail page; confirm matches before buying.

Should I replace coils and plugs together?
If your vehicle has over 80,000 km or shows misfires and slow acceleration, replacing both at once helps ensure consistent ignition performance.

Do the spark plugs use iridium?
Yes, the plugs use an iridium electrode designed for quicker starts and longer life compared with standard plugs.