Denso 5301 Spark Plug

Denso Iridium Power Spark Plug 5301

Denso Iridium Power 5301 is a performance spark plug built for precise ignition response and stable combustion. It uses a 0.4 mm iridium center electrode, a tapered-cut U-groove ground design, and a 1.1 mm pre-gap to support consistent spark delivery in a wide range of import and domestic applications.

Key Features

• Iridium center electrode tip material for fine-wire ignition performance
• World’s smallest 0.4 mm iridium center electrode design
• Tapered-cut, U-groove ground electrode tip design
• Nickel ground electrode core with copper center electrode core
• 5000 ohm resistance for ignition system compatibility
• 14.0 mm thread diameter, 19.0 mm reach, and flat seat design
• Manufacturer heat range 16 with a 16 mm hex size

Iridium Power Line Details

The Denso Iridium Power line focuses on fine-wire electrode construction for sharper ignition response and efficient spark concentration. Part number 5301 follows that approach with a small-diameter iridium tip and a tapered U-groove ground electrode profile, making it a direct-fit spark plug choice for drivers servicing older BMW, Mercedes-Benz, Toyota, Honda, Saab, and Nissan applications.

Detailed Description

This Denso 5301 spark plug is engineered for vehicles that call for a flat-seat, 14 mm plug with a 19 mm reach. The iridium tip and copper-core center electrode help maintain a stable spark path, while the ground electrode design supports consistent flame initiation across a broad operating range. It cross-references Denso Auto Parts IQ16 for the same application.

Compatible fitment includes long-tail searches such as Denso 5301 spark plug for 1990-1993 Mercedes-Benz 300SL, Denso Iridium Power 5301 for 1986-1993 Toyota Celica, and Denso 5301 for 1999-2002 Saturn SL2. It also appears in applications for BMW 750iL, Honda CRX, and Nissan Pathfinder, depending on engine specification.

What It Helps Address

• Hard starting caused by worn or eroded spark plug electrodes
• Misfire concerns from weak or inconsistent spark output
• Rough idle related to aged ignition components
• Reduced throttle response from degraded plug performance
• Maintenance intervals where a direct-fit iridium plug is specified

Installation Notes and Tips

Verify thread diameter, reach, seat type, and heat range before installation. Confirm the vehicle’s OE plug specification and gap requirement; this plug is supplied with a 1.1 mm pre-gap. Use proper spark plug service procedures, and check for application-specific notes such as the 1998 Mercedes-Benz E320 listing that requires two spark plugs per cylinder. Confirm fitment for vehicles such as BMW 850Ci, Mercedes-Benz E420, and Toyota Supra by engine code when available.

Quality Assurance

Denso manufactures this Iridium Power spark plug to OE-style dimensional standards with iridium fine-wire construction and application-specific electrical resistance. Part number 5301 is listed across multiple OEM cross-references and fitment records for 1981-2011 vehicles, including Toyota, Mercedes-Benz, BMW, Honda, and Saturn applications.