Denso 4111 Spark Plug

Denso 4111 U-Groove Spark Plug

Denso 4111 is a conventional spark plug built around a U-groove ground electrode design for improved ignitability and more consistent combustion. It uses a copper center electrode core with nickel tip materials and a nickel ground electrode to support stable spark delivery in secondary ignition systems.

Key Features

• U-groove ground electrode tip design for stronger spark exposure
• 5000 ohm resistance for controlled electrical performance
• Copper center electrode core with nickel center tip
• Nickel ground electrode with standard ground configuration
• Flat seat design, 12.00 mm thread diameter, 19.00 mm reach
• Pre-gapped to 0.9 mm
• Manufacturer heat range 27
• Compatible With select Honda Civic and Toyota Corolla applications where this plug specification is required

Product Details

The Denso U-Groove Conventional line focuses on ignition efficiency through electrode geometry rather than complex construction. On part number 4111, the U-shaped ground electrode helps expose the spark kernel more effectively, while the copper core and nickel electrode materials support dependable heat transfer and steady ignition performance. This spark plug is a practical OE-style service part for drivers maintaining factory-style ignition behavior in vehicles such as Honda Civic and Toyota Corolla applications that call for this specification. This part cross-references DENSO Auto Parts (e.g., X27EPR-U9) for the same application.

Common Issues This Part Can Address

• Hard starting caused by worn or fouled spark plugs
• Rough idle from inconsistent ignition firing
• Misfire conditions tied to degraded plug electrodes
• Reduced fuel efficiency from weak spark delivery
• Loss of throttle response from aged secondary ignition components

Installation Notes and Tips

Verify the thread diameter, reach, seat type, and heat range against the vehicle service specification before installation. Check the gap at 0.9 mm prior to use, and inspect ignition wires or coil-on-plug components for wear so the new plug is not installed into a compromised ignition system. For Honda Civic and Toyota Corolla service work, confirm the exact engine application and plug specification listed by the vehicle manufacturer.

Quality Assurance

Denso is a recognized OE supplier in ignition components, and the U-Groove Conventional design is built to deliver consistent spark exposure and reliable service characteristics. Part number 4111 is manufactured to the listed specifications for accurate replacement selection.