Denso 4708 Spark Plug

Denso Iridium TT Spark Plug 4708

The Denso Iridium TT 4708 spark plug is built for drivers who want OE-style durability with a performance-focused ignition upgrade. It combines an iridium center electrode with a platinum twin-tip ground design to support consistent spark delivery, smoother combustion, and dependable throttle response.

Compatible With a wide range of import and domestic applications, including Honda Accord, Toyota Corolla, BMW 535i, and Hyundai Sonata fitments, this spark plug is a practical replacement for high-mileage engines and routine tune-ups. The Denso 4708 is also a direct cross-reference for DENSO Auto Parts IW16TT.

Key Features

• Iridium center electrode tip for precise spark delivery
• Platinum twin-tip ground electrode design for stable ignition performance
• Copper core center electrode and nickel ground core for balanced heat transfer
• 5000 ohm resistance for modern ignition system compatibility
• Flat seat design with 14.00 mm thread diameter and 19.00 mm reach
• Pre-gapped at 1.0 mm for installation consistency
• Manufacturer heat range 16

Product Details

Denso’s Iridium TT line is positioned as an OE-style spark plug family that blends long service life with stronger ignition characteristics. The twin-tip electrode layout helps maintain a focused spark kernel, while the iridium center tip supports reliable firing under demanding operating conditions. For vehicles such as Hyundai Sonata, Kia Optima, and Toyota 4Runner applications, that combination helps maintain steady idle quality and responsive engine operation.

Part number 4708 is specified for a broad range of vehicles across multiple makes and model years, including BMW, Chrysler, Dodge, Honda, Jaguar, Land Rover, Mitsubishi, Nissan, Porsche, Suzuki, Toyota, Volkswagen, and others listed in the fitment data. If you are replacing worn plugs on a high-mileage engine or servicing a vehicle that calls for an OE-style iridium plug, this Denso spark plug is built to match those requirements.

What It Helps Address

• Hard starting caused by worn or fouled spark plugs
• Rough idle and inconsistent combustion
• Misfire symptoms related to weak ignition output
• Reduced throttle response from degraded plug performance
• Maintenance intervals where OE-style replacement is needed

Installation Notes

Verify the vehicle’s spark plug specification before installation, including thread diameter, reach, seat type, and heat range. The plug is pre-gapped at 1.0 mm, but gap verification is still recommended before use. Follow the manufacturer’s torque specification and inspect ignition components such as coils, wires, and boots during service. Fits 1990-2005 Hyundai Sonata, N/A; Fits 2001-2006 Kia Optima, N/A; Fits 1984-1995 Toyota 4Runner, N/A; Fits 1986-1989 Honda Accord, N/A; Fits 1985-1993 BMW 535i, N/A.

Quality Assurance

Denso manufactures the Iridium TT line to combine OE-style durability with performance-oriented ignition design. The 4708 uses iridium and platinum electrode materials selected for stable spark characteristics and long-term service in the listed applications.