Marsram Ignition Coil Pack and Double-Iridium Spark Plug Kit FD505 for 2003–2007 Ford Focus 2.3L — 4-Coil/4-Plug Direct Fit

This kit bundles four high-conductivity ignition coils and four long-life double-iridium spark plugs made to match original-equipment fit and performance for a wide range of 2003–2013 Ford Focus, Escape, Transit Connect, select Mazda 3/Tribute, and Mercury Mariner models. Components are engineered to resist heat and corrosion while delivering consistent spark timing and combustion efficiency. The package also covers many common OEM part numbers (e.g., 4M5Z12029A/B, DG504, UF621) so you can replace faulty coils or worn plugs in one service.

Will this coil and plug kit fit my vehicle?

Compatibility spans several model years and engine codes; always verify fit with the vehicle compatibility tool before ordering. The kit is intended for numerous 2.0–2.3L four-cylinder engines across Ford, Mazda, and Mercury ranges where FD505 or equivalent coils were used.

• Fits many Ford Focus (2003–2011) and Escape/Mariner (2005–2008) variants
• Compatible with Mazda 3 and Tribute models listed for 2004–2008
• Replaces OEM numbers such as 4M5Z12029A/B, DG504, UF621 and more
• Check "Amazon Confirm Fit" or vehicle VIN fitment before purchase

What improvements can I expect after installing this kit?

Replacing old coils and worn plugs typically reduces misfires, smooths idle, and restores throttle response. The double-iridium spark plugs sustain a stable gap and resist corrosion, while epoxy-encapsulated coils tolerate engine heat for more consistent sparks.

• Stronger, steadier ignition under load for quicker acceleration
• Reduced rough idling and fewer engine hesitation events
• Longer service life from corrosion-resistant plug electrodes
• Improved starting reliability in varied temperatures

How are these coils and plugs built differently from cheaper aftermarket parts?

Marsram coils use high-strength engineering plastics and epoxy resin to prevent heat damage, plus copper windings for faster energy transfer. The AP104 spark plugs use a double-iridium center and ground electrode for consistent spark performance and minimal gap growth over time.

• Epoxy and reinforced housing resist melting and cracking
• High-conductivity copper coil windings for rapid ignition
• Double-iridium electrodes for sustained spark and efficiency
• Manufacturing and testing aimed at OE-level durability

Is installation straightforward for a DIYer or do I need a mechanic?

These coils and plugs are designed to meet or exceed OE specifications and generally install using common hand tools. Basic mechanical experience is enough for many DIYers, but follow safety procedures and torque specs; seek professional help if you’re unsure.

• Direct-fit coils and threaded spark plugs for straightforward replacement
• Recommended torque and gap checks ensure proper seating and performance
• Package contains four coils and four plugs for a cylinder bank service
• Contact Marsram support for warranty assistance if issues arise

Who this is for: This Marsram FD505 coil pack and AP104 spark plug kit suits owners and technicians working on compatible Ford, Mazda, and Mercury 2.0–2.3L four-cylinder engines who want a cost-effective, OE-style replacement to address ignition faults, rough running, or declining performance. It’s particularly useful for maintenance when multiple coils or plugs show wear, and for shoppers who prefer replacing a full set at once to restore consistent engine behavior.