DENSO 4187 U-Groove Nickel Spark Plug

The DENSO 4187 (U31ESR-N) spark plug is engineered to deliver optimal performance and reliability for your vehicle's ignition system, featuring a copper center electrode core with a nickel tip for efficient combustion and enhanced engine performance.

U-Groove Technology:

U-Groove is an innovative design that helped make DENSO spark plugs famous. The plug employs a unique, channeled ground electrode designed to generate a larger spark nucleus at the point of ignition. Greater spark energy than ordinary plugs means improved flame travel, producing more complete, consistent, and efficient combustion for greater fuel efficiency and improved throttle response.

Key Features:

• 14.00mm thread diameter with 19.00mm reach and flat seat type
• 16.0mm hex size with 0.8mm pre-gap and 5000 ohms resistance
• 360-degree laser-welded construction, 100 percent pre-fired to ensure reliable operation
• Copper core center electrode for superior thermal conductivity
• Copper glass seal helps heat dissipation with deeply inserted copper core
• Unique 5-rib insulator reduces flashover and decreases voltage loss
• Precision machine-rolled threads reduce seizing and cross-threading in delicate aluminum heads
• Heat-resistant nickel plating provides excellent durability and stability under various driving conditions

Note: This plug has a threaded terminal stud and does not contain a terminal nut. If a terminal nut is needed, order part #067606-0051 separately.

This spark plug lasts twice as long as conventional plugs and is original equipment in many automotive applications. Cross-reference numbers include OEM 067700-5640, 09482-00461, and NGK CR10E.