Denso 3421 Spark Plug

Overview of Denso Iridium Long Life Spark Plug 3421

The Denso Iridium Long Life Spark Plug 3421 is engineered for reliable ignition performance in a variety of vehicles including BMW, Honda, Lexus, and Toyota models. Designed with advanced materials, this spark plug supports efficient combustion and long service intervals.

• Iridium center electrode tip for enhanced durability
• Platinum chip ground electrode tip design
• Copper core center electrode for improved conductivity
• Standard ground configuration with nickel core ground electrode
• Pre-gap size of 1.1 mm for optimal spark
• Flat seat type with 14 mm thread diameter and 26.5 mm reach
• Manufacturer heat range rating of 20
• Hex size of 16.0 mm for installation
• Resistance of 5000 ohms to reduce electrical noise

Details on Denso Iridium Long Life Spark Plug Technology

The Iridium Long Life product line by Denso focuses on delivering extended durability and consistent ignition performance. The use of an iridium center electrode tip combined with a platinum chip on the ground electrode tip enhances wear resistance and maintains stable spark over time. Copper core center electrodes improve thermal conductivity, helping to dissipate heat effectively. This spark plug’s design supports efficient combustion, which can contribute to smoother engine operation and fuel efficiency in compatible vehicles.

Compatible Vehicles and Applications

This spark plug is compatible with a wide range of makes and models, including BMW 3 Series variants like the 328i and 330i, Honda Civic, Lexus GX460, Toyota 4Runner, and Nissan Maxima among others. It is suitable for secondary ignition systems requiring a 14 mm thread diameter and a 26.5 mm reach. The Denso 3421 spark plug is designed to meet the ignition needs of both performance and daily driving vehicles.

• Resolves misfires and rough idling issues
• Helps improve cold start performance
• Reduces engine knocking and pinging
• Supports consistent spark delivery for smoother acceleration
• Minimizes electrical interference with onboard electronics

Installation Notes and Tips

When installing the Denso Iridium Long Life Spark Plug 3421, ensure the pre-gap size of 1.1 mm is maintained for optimal performance. Use a 16 mm socket wrench for proper tightening to the manufacturer’s torque specifications. The flat seat design requires careful seating to avoid leaks. It is recommended to inspect the ignition system components and replace spark plugs in sets to maintain balanced engine operation.

Quality Assurance and Warranty

Denso manufactures the Iridium Long Life spark plugs to meet strict quality standards, ensuring reliable performance and longevity. The use of premium materials such as iridium and platinum contributes to the spark plug’s durability. While specific warranty details may vary, Denso products typically come with manufacturer-backed warranties covering defects in materials and workmanship.