Denso 4101 Spark Plug

Denso 4101 U-Groove Spark Plug Overview

The Denso 4101 spark plug is part of the U-Groove Conventional line, built for drivers who want a straightforward secondary ignition replacement with OE-style dimensions and materials. Its U-groove ground electrode design is engineered to improve ignitability, helping support more efficient combustion in the right application.

Use this Denso 4101 spark plug when you need a conventional replacement with a 12.0 mm thread diameter, 19.00 mm reach, flat seat, and 0.7 pre-gap. It is a practical choice for ignition service on select Asian vehicle applications, including Honda Civic and Toyota Corolla search queries where the correct plug specification matters.

Key Features

• U-Groove ground electrode tip design for improved ignitability
• 5000 ohm resistor for stable secondary ignition performance
• Copper center electrode core for reliable heat transfer
• Nickel center and ground electrode tip materials
• Standard ground configuration with one ground electrode
• 0.7 pre-gap size for specified applications
• 12.00 mm thread diameter, 19.00 mm reach, and 18.0 mm hex size
• Flat seat design for proper cylinder head sealing in the correct engine

Product Details

Denso U-Groove Conventional spark plugs are designed around a simple, durable electrode layout that supports consistent spark delivery in compatible engines. The U-shaped ground electrode helps expose the spark kernel more effectively than a conventional flat ground design, while the copper core and nickel electrode materials support dependable heat management and service life in the intended application. Part number 4101 is also referenced as Denso X24ESR-U for cross-reference purposes.

For fitment-based searches, this plug is commonly researched for Honda Civic and Toyota Corolla ignition service, but final application must match the engine’s specified plug dimensions and heat range. The Denso 4101 is a direct-fit style spark plug for engines calling for a 24 manufacturer heat range, 5000 resistance, and the listed thread, reach, and seat configuration.

Common Issues This Part Can Address

• Hard starting caused by worn or fouled spark plugs
• Rough idle from inconsistent spark delivery
• Misfire conditions related to electrode wear
• Reduced fuel efficiency from degraded ignition performance
• Weak combustion in engines requiring the specified plug design

Installation Notes and Tips

Verify the engine’s required thread diameter, reach, seat type, heat range, and pre-gap before installation. Use the correct torque specification for the cylinder head material, and inspect ignition wires or coils during service so the new plug is not installed into a worn secondary ignition system. For Honda Civic and Toyota Corolla applications, confirm the exact engine code and plug specification against the vehicle service information before replacing the old plug with Denso 4101.

Quality Assurance

Denso manufactures this spark plug as part of its U-Groove Conventional product line, using established OE-style construction and specified electrode materials for consistent ignition service. Part number 4101 is built to the listed dimensions and electrical characteristics for the intended application.