Denso 3401 Spark Plug

Denso Iridium Long Life Spark Plug 3401

Denso 3401 is an Iridium Long Life spark plug built for OE-level ignition performance, durability, and emissions control. It is a direct-fit secondary ignition component for select Honda applications, including Honda Fit and Honda Accord models listed below.

Key Features

• Iridium center electrode tip for stable spark performance
• Platinum chip ground electrode tip design
• 5000 ohm resistor for ignition noise suppression
• Copper core center electrode and nickel core ground electrode construction
• 14.00 mm thread diameter, 19.00 mm reach, and 16.0 mm hex size
• Flat seat design with 1.3 pre-gap size
• Manufacturer heat range 20

Product Details

The Denso Iridium Long Life line is engineered for drivers who want an OE-style spark plug with durable electrode materials and consistent ignition characteristics. Part number 3401 uses an iridium center electrode tip, a platinum chip ground tip, and a resistor design to support clean spark delivery and reduced electrical interference. For Honda Fit and Honda Accord applications, this spark plug matches the listed thread, reach, seat, and gap specifications for proper cylinder head fitment.

This part cross-references Denso Auto Parts SKJ20DR-M13 for the same application.

Fitment

• Fits 2007-2013 Honda Fit, N/A
• Fits 2007 Honda Accord, N/A, SULEV
• Fits 2003-2005 Honda Accord, N/A, California exempt parts can be used on pollution controlled vehicles in California.

Common Issues This Can Address

• Hard starting caused by worn spark plug electrodes
• Rough idle from inconsistent ignition output
• Misfire conditions related to plug wear or incorrect gap
• Reduced fuel economy from degraded spark performance
• Ignition noise concerns in resistor-equipped systems

Installation Notes and Tips

Verify the engine application against the listed Honda Fit and Honda Accord fitment before installation. Confirm the 14.00 mm thread diameter, 19.00 mm reach, flat seat, and 1.3 pre-gap size match the original specification. Inspect the ignition system, torque the plug to the vehicle manufacturer’s specification, and check for contamination or carbon buildup in the plug wells before installing Denso 3401.

Quality Assurance

Denso manufactures this spark plug to meet strict OE performance, durability, and emissions standards. The Iridium Long Life design uses durable electrode materials and OE-style construction for consistent service in the listed Honda applications.