Denso 4030 Spark Plug

Denso 4030 U-Groove Spark Plug Overview

The Denso 4030 spark plug is a conventional ignition component built with a U-Groove ground electrode to improve ignitability and support more efficient combustion. It is a direct-fit style spark plug for applications that call for a 14 mm thread, flat seat, 19.00 mm reach, and a 0.8 pre-gap.

For drivers and technicians searching for a Denso spark plug for Honda Civic or Toyota Corolla service, this part number 4030 offers a copper core center electrode with nickel tip materials for dependable secondary ignition performance.

Key Features

• U-Groove ground electrode tip design for improved spark exposure
• Conventional spark plug construction for standard ignition service
• Copper core center electrode for stable heat transfer
• Nickel center and ground electrode tip materials
• Pre-gapped to 0.8 for specified applications
• 14.00 mm thread diameter with flat seat and 19.00 mm reach
• 20.6 hex size for proper socket fitment
• Manufacturer heat range 24

Product Details

Denso U-Groove Conventional spark plugs are engineered around a ground electrode shape that opens the spark path for better ignitability. That design can help support cleaner combustion and consistent engine efficiency when the ignition system is serviced with the correct OE-style plug. The Denso 4030 is built with a standard ground configuration, one ground electrode, and a copper core center electrode to balance conductivity and durability in everyday driving conditions.

This part cross-references DENSO Auto Parts W24ES-U for the same application. If you are replacing worn plugs in a Honda Civic, Toyota Corolla, or another vehicle that specifies this plug configuration, part number 4030 is the reference to verify against the original service specification.

What This Spark Plug Helps Address

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

Installation Notes and Tips

Confirm thread diameter, reach, seat type, and heat range before installation. Use the specified gap setting for the application and inspect the ignition coil, plug wires, and cylinder head threads during service. For Honda Civic and Toyota Corolla maintenance, match the replacement plug to the engine’s original specification rather than relying on appearance alone.

Quality Assurance

Denso is known for OE-level ignition component engineering, and the U-Groove Conventional line focuses on practical spark performance for standard replacement service. Verify fitment by engine code and service manual requirements before installation.