DENSO 4170 X31ETR Multi-Ground Standard Spark Plug

The DENSO 4170 (X31ETR) is a multi-ground, standard nickel spark plug engineered for reliable ignition performance across a wide range of small engine, marine, and powersports applications. Featuring a dual ground electrode design and a fully projected insulator, this plug delivers consistent combustion and long-lasting durability.

Key Features:

• Dual ground electrode design — two ground electrodes increase durability and extend service life
• Fully projected insulator — reduces carbon fouling for dependable ignition
• Machine rolled threads — prevent seizing or cross-threading during installation and removal
• 100% pre-fired — every plug is pre-fired at the factory to ensure the highest quality
• Purified alumina powder insulator — delivers exceptional strength and thermal conductivity
• Five-rib insulator design — prevents flashover
• Copper-glass seal — bonds the center electrode and insulator for a gas-tight seal
• 5k Ohm resistor — suppresses electromagnetic interference
• Made in Japan

Specifications:

• Thread Diameter: 12mm
• Thread Pitch: 1.25mm
• Seat Type: Gasket
• Reach: 19mm (3/4")
• Hex Size: 18mm
• Terminal Type: Threaded Stud (terminal nut not included)
• Electrode Gap: 0.028" (0.7mm)
• Center Electrode Material: Nickel, 2.5mm, Projected
• Ground Electrode: Nickel, Multi-Ground
• Heat Range: 31
• Torque Specs: 11–18 lb-ft (cast iron and aluminum heads)
• Resistor Value: 5k Ohm
• Warranty: 12 months / 20,000–30,000 miles
• Cross Reference: 067700-5140, NGK 1299 (JR10B)

The DENSO X31ETR is a direct OEM-quality replacement spark plug trusted by leading vehicle manufacturers. Its multi-ground electrode configuration and copper-core construction ensure efficient heat transfer and consistent firing across a broad range of engine types.