Denso 4135 Spark Plug

Denso 4135 U-Groove Spark Plug Overview

Denso 4135 is a conventional spark plug built for reliable secondary ignition performance in applications that call for a 14 mm, flat-seat plug with a 19.00 mm reach. The U-Groove design is engineered to improve ignitability, helping support smoother combustion and consistent engine operation.

For drivers searching for a Denso spark plug 4135 replacement, this U-Groove Conventional plug combines a copper center electrode core with nickel tip materials and a multi-electrode ground design. It is a practical choice for ignition service on vehicles such as Honda Civic and other applications that specify this plug configuration.

Key Features

• Denso U-Groove Conventional spark plug, part number 4135
• U-Groove electrode profile for improved spark exposure and ignitability
• Multi-electrode ground configuration with two ground electrodes
• Copper center electrode core for stable conductivity
• Nickel center and ground electrode tip materials
• 5000 ohm resistance for ignition system noise control
• 0.7 pre-gap size, 16.0 hex size, flat seat, 14.00 thread diameter
• Manufacturer heat range 31

Product Details

The Denso U-Groove Conventional line focuses on dependable ignition performance with a design that helps the spark kernel form more efficiently at the plug gap. On this Denso 4135 spark plug, the copper core supports heat transfer and electrical conductivity, while the nickel electrode materials provide a conventional serviceable construction for everyday engine maintenance. The multi-electrode ground setup is designed to maintain consistent spark exposure under normal operating conditions.

This spark plug is a fitment-specific ignition component for vehicles that call for the listed dimensions and seat style. If you are replacing worn plugs on a Honda Civic or sourcing a Denso 4135 spark plug for other exact-match applications, verify thread diameter, reach, heat range, and seat type before installation.

This part cross-references DENSO Auto Parts (e.g., U31ETR) for the same application.

What It Helps Address

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

Installation Notes and Tips

Confirm the vehicle’s required thread diameter, reach, seat type, heat range, and pre-gap before installation. Use the specified gap setting for the application, and inspect ignition wires or coil-on-plug components at the same time to avoid repeat misfire concerns. For Honda Civic spark plug service or other exact-fit applications, follow the manufacturer’s service procedure and torque specification.

Quality Assurance

Denso manufactures this U-Groove Conventional spark plug as a technical ignition component built around established electrode and material specifications. Part number 4135 is intended for exact-match applications where the listed dimensions and ignition characteristics are required.