Denso 4008 Spark Plug

Denso 4008 U-Groove Spark Plug

The Denso 4008 is a conventional spark plug built around a U-Groove ground electrode design for improved ignitability and more consistent combustion. It uses a copper center electrode core with nickel tip materials and a standard ground configuration for dependable secondary ignition performance.

Key Features

• U-Groove ground electrode tip design for stronger spark exposure
• Copper center electrode core for efficient heat transfer
• Nickel center and ground electrode tip materials
• 5000 ohm resistance for ignition system compatibility
• Pre-gapped to 0.7 mm
• 14.00 mm thread diameter, 12.70 mm reach, and flat seat design
• 16.0 mm hex size for proper socket fitment

Detailed Description

Built for drivers who need a straightforward replacement spark plug, the Denso 4008 combines a conventional construction with a U-Groove electrode profile that helps expose the spark kernel more effectively. That design supports cleaner ignition events and steady engine operation in everyday driving. This part number 4008 is also referenced as Denso Auto Parts U22FSR-U, and it is a practical choice for service work on vehicles such as Honda Civic and Toyota Corolla applications where the correct plug specification is required.

The Denso U-Groove Conventional line focuses on reliable ignition performance using proven materials and dimensions. With a copper core, nickel tips, and a standard ground configuration, this spark plug is built to match the needs of engines that call for a flat-seat plug with a 14 mm thread and 12.70 mm reach. For buyers searching for Denso 4008 spark plug fitment, Denso 4008 replacement, or U-Groove spark plug for Honda Civic and Toyota Corolla, this part provides the core specifications needed for accurate selection.

What It Helps Address

• Hard starting caused by worn or inefficient spark plugs
• Rough idle from weak or inconsistent ignition
• Misfire conditions related to degraded plug performance
• Reduced combustion efficiency from excessive electrode wear
• Service replacement needs for specified Honda Civic and Toyota Corolla applications

Installation Notes and Tips

Verify thread diameter, reach, seat type, and heat range against the vehicle service specification before installation. The Denso 4008 uses a flat seat, 14.00 mm thread diameter, 12.70 mm reach, and 16.0 mm hex size, so the correct socket and torque procedure should be used. Check the gap against the engine specification even though the plug is pre-gapped to 0.7 mm, and confirm ignition wire or coil condition during service.

Quality Assurance

Denso’s U-Groove Conventional spark plug line is built around established OE-style ignition engineering and material choices for consistent service replacement performance. This part cross-references DENSO Auto Parts (e.g., U22FSR-U) for the same application.