Denso 3491 Spark Plug

Reliable Ignition Performance for Lexus and Toyota Vehicles

The Denso Iridium Long Life (SIP) spark plug, part number 3491, is engineered to provide consistent ignition performance for a range of Lexus and Toyota models. Designed with advanced materials and precise specifications, this spark plug supports efficient combustion and engine reliability.

• Iridium center electrode tip for enhanced durability and ignition
• Platinum needle ground electrode tip with needle-to-needle configuration
• Copper core center electrode for optimal conductivity
• Three ground electrodes with nickel core material for stable spark
• Pre-gap size of 0.8 mm and flat seat type for proper fit and function
• 16 mm hex size and 14 mm thread diameter for compatibility
• Manufacturer heat range rating of 20 for balanced thermal performance
• 26.50 mm reach to match OEM specifications
• Resistance of 5000 ohms to reduce electrical noise interference

About the Iridium Long Life (SIP) Product Line

The Iridium Long Life (SIP) line from Denso focuses on delivering spark plugs with extended service life and reliable ignition characteristics. Utilizing iridium at the center electrode tip and platinum on the ground electrode tip, these spark plugs are designed to maintain stable spark performance over time, reducing the need for frequent replacements. This product line is suitable for vehicles requiring precise ignition components that meet OEM standards.

Technical Details and Compatibility

The Denso 3491 spark plug features a copper core center electrode that enhances electrical conductivity, paired with an iridium tip to withstand high temperatures and wear. The ground electrode uses a platinum needle tip in a needle-to-needle configuration, supported by a nickel core for durability. With a pre-gap size of 0.8 mm and a flat seat type, this spark plug ensures proper sealing and spark gap consistency. The 16 mm hex size and 14 mm thread diameter align with factory specifications, making it compatible with various Lexus and Toyota models including Avalon, Camry, ES350, GS350, GS450h, Highlander, IS300, IS350, LC500h, LS500h, RC300, RC350, RX350, RX350L, RX450h, RX450hL, Sienna, and Tacoma.

Common Applications and Problem Solving

• Restores efficient ignition in Lexus RX350 and Toyota Camry engines
• Reduces misfires and rough idling in Toyota Highlander and Tacoma
• Improves fuel combustion stability in Lexus IS350 and GS450h
• Addresses spark plug wear and electrode erosion in Lexus LS500h
• Supports hybrid engine ignition needs in Lexus RX450h and LC500h

Installation Notes and Tips

When installing the Denso 3491 spark plug, ensure the pre-gap of 0.8 mm is maintained for optimal performance. Use a torque wrench to tighten the spark plug to manufacturer specifications to avoid damage to the flat seat and ensure proper sealing. This spark plug is designed for direct replacement in compatible Lexus and Toyota models without modification.

Quality Assurance and Warranty

Denso manufactures the 3491 spark plug to meet strict OEM standards, ensuring reliable performance and durability. The use of iridium and platinum materials contributes to extended service life. While specific warranty details are not provided, Denso products typically adhere to industry quality controls and are backed by the brand's reputation for automotive ignition components.