Denso 4038 Spark Plug

Denso 4038 U-Groove Spark Plug

Denso 4038 is a conventional spark plug built around a U-Groove ground electrode to improve ignitability and support more efficient combustion. It is a practical OE-style ignition service part for drivers looking for a direct replacement spark plug with copper and nickel electrode construction.

Key Features

• U-Groove ground electrode tip design for improved spark exposure
• Standard ground configuration with a single ground electrode
• Copper center electrode core for reliable heat transfer
• Nickel center and ground electrode tip materials
• Pre-gapped to 0.7 mm
• 14.00 mm thread diameter, 12.70 mm reach, flat seat
• Manufacturer heat range 24
• Cross-reference: DENSO Auto Parts W24FS-U

Product Details

The Denso U-Groove Conventional line focuses on straightforward ignition performance with a design that helps the spark kernel form more efficiently at the plug gap. On this Denso 4038 spark plug, the U-shaped ground electrode, copper core center electrode, and nickel contact materials work together to provide stable secondary ignition service in applications that call for a conventional plug design. This part number is commonly searched as Denso 4038 and W24FS-U, making it easier to match the correct ignition service part for your vehicle maintenance needs.

For shoppers comparing ignition parts for Honda Civic, Toyota Corolla, or similar compact-car applications, Denso 4038 is the type of spark plug often selected when the goal is a direct OE-style replacement with the correct thread size, reach, seat type, and pre-gap specification. The part number 4038 is also useful when cross-checking catalog listings against Denso W24FS-U.

Common Issues This Spark Plug Can Address

• Hard starting caused by worn or fouled spark plugs
• Rough idle from weak or inconsistent ignition output
• Misfire symptoms related to excessive electrode wear
• Reduced fuel efficiency from degraded spark performance
• Loss of throttle response from an aging ignition service part

Installation Notes and Tips

Verify thread diameter, reach, seat type, and heat range against the vehicle service specification before installation. The pre-gap is set at 0.7 mm, but final gap should always be checked against the engine requirement. Use proper spark plug removal and installation procedures to avoid thread damage in the cylinder head, and confirm the plug is tightened to the manufacturer’s specified torque.

Compatible With Honda Civic and Toyota Corolla applications where the catalog calls for Denso 4038 or W24FS-U. For vehicle-specific service, confirm the exact year, engine, and ignition specification before ordering.

Quality Assurance

Denso is an established OE supplier in ignition components, and the U-Groove Conventional product line is built for consistent fit and dependable secondary ignition service. This part is identified by Denso 4038 and the interchange reference W24FS-U for catalog matching.