Denso 4174 Spark Plug

Denso 4174 U-Groove Spark Plug Overview

The Denso 4174 is a conventional spark plug built for steady ignition performance in secondary ignition systems. Its U-groove electrode design helps improve ignitability, supporting more efficient combustion in everyday driving and maintenance service.

For drivers searching for a Denso spark plug for Honda Civic or Toyota Corolla tune-up service, this part number 4174 offers a straightforward OE-style replacement with the core materials and dimensions needed for proper fit and function.

Key Features

• U-groove electrode design for improved spark exposure and ignitability
• Copper center electrode core for reliable heat transfer
• Nickel center and ground electrode tip materials
• Standard ground configuration and standard ground electrode tip design
• 5000 ohm resistance for ignition system noise control
• 14.00 mm thread diameter, 19.00 mm reach, and flat seat type
• 0.8 pre-gap size for consistent installation setup
• 16.0 mm hex size for common spark plug service tools

Detailed Product Description

Denso 4174 is part of the U-Groove Conventional line, a product line focused on practical ignition service with a design that increases spark exposure at the plug gap. The U-shaped ground electrode helps the spark form more readily, which can support smoother combustion and more efficient engine operation when replacing worn plugs. This spark plug uses a copper core center electrode, nickel tip materials, and a standard single-ground configuration for dependable everyday use.

With a 14.00 mm thread diameter, 19.00 mm reach, flat seat, and 0.8 pre-gap size, the Denso 4174 is built for applications that call for these exact specifications. It is a direct service part for ignition maintenance on vehicles such as Honda Civic and Toyota Corolla, and the part number 4174 is also referenced by DENSO Auto Parts U22ESR-N for the same application.

What This Spark Plug Helps Address

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

Installation Notes and Tips

Verify thread diameter, reach, seat type, and pre-gap against the vehicle service specification before installation. Use the correct 16.0 mm spark plug socket and inspect the ignition system, plug wires, or coil components during service. For fitment-based searches, this Denso spark plug is commonly sought for Honda Civic and Toyota Corolla maintenance, but final application should always match the engine specification for the vehicle.

Quality Assurance

Denso manufactures ignition components to OE-level dimensional and material standards, and the U-Groove Conventional line is built around consistent spark formation and serviceable everyday performance. Part number 4174 is specified with defined resistance, heat range, and electrode construction for accurate replacement selection.