Denso 4006 Spark Plug

Denso 4006 U-Groove Spark Plug

The Denso 4006 is a conventional spark plug built around a U-groove ground electrode design for stronger ignitability and more consistent combustion. It is a practical choice for drivers searching for a Denso spark plug for ignition service on applications such as Honda Civic and Toyota Corolla maintenance.

Key Features

• U-groove ground electrode tip design for improved spark exposure
• Nickel ground electrode tip with a nickel center electrode tip
• Copper center electrode core for stable heat transfer
• Standard ground configuration with a single ground electrode
• Pre-gapped to 0.7 mm for straightforward service replacement
• 14.00 mm thread diameter, 12.70 mm reach, and flat seat design
• 16.0 mm hex size for common spark plug service tools
• Manufacturer heat range 22

Product Details

As part of Denso’s U-Groove Conventional line, this spark plug focuses on dependable secondary ignition performance with a design that helps expose the spark kernel more effectively. The copper core supports heat dissipation, while the nickel electrode materials provide a conventional service-plug construction suited to routine tune-ups. If you are replacing a worn plug in a Honda Civic or Toyota Corolla, the Denso 4006 offers the core dimensions and electrode layout needed for a direct spark plug replacement where specified by the vehicle application.

This part cross-references DENSO Auto Parts (e.g., U22FS-U) for the same application.

What It Helps Address

• Hard starting caused by worn or fouled spark plugs
• Rough idle from weak or inconsistent spark delivery
• Misfire conditions related to degraded ignition performance
• Reduced fuel efficiency from incomplete combustion
• Loss of throttle response during routine ignition wear

Installation Notes and Tips

Verify thread diameter, reach, seat type, and heat range against the vehicle service specification before installation. Use the correct 16.0 mm spark plug socket, inspect the ignition coil or plug wire condition, and confirm the gap matches the engine requirement if the application calls for a different setting than the pre-gap size. For Honda Civic and Toyota Corolla service, follow the manufacturer torque specification and inspect the old plug for signs of oil, carbon, or coolant contamination.

Quality Assurance

Denso manufactures this plug as part of its U-Groove Conventional spark plug line, using a conventional nickel-and-copper construction with a focus on reliable ignitability and efficient combustion support. Part number 4006 is built to the listed dimensions and electrode specifications for service replacement where the application calls for this design.