Denso 3517 Spark Plug

Denso Iridium Long Life Spark Plug

Denso 3517 is an Iridium Long Life (SIP) spark plug built for OE-style ignition performance in select Toyota applications. It uses an iridium center electrode, platinum needle ground tip, and a 0.9 mm pre-gap to support consistent spark delivery and stable combustion.

For Toyota Corolla, Prius, Prius AWD-e, and Prius Prime applications, this spark plug is specified to match factory-style dimensions and electrical characteristics. The Denso 3517 is a direct-fit ignition service part for drivers replacing worn plugs on covered Toyota models.

Key Features

• Iridium center electrode tip material for long-life ignition service
• Platinum needle ground electrode tip design with needle-to-needle ground configuration
• 5000 ohm resistance for OE-style electrical performance
• Copper center electrode core and nickel ground electrode core
• Flat seat design with 12.00 mm thread diameter and 14.3 mm hex size
• Manufacturer heat range 16 and 26.50 mm reach
• Pre-gapped to 0.9 mm

Product Details

The Denso Iridium Long Life (SIP) line focuses on OE replacement spark plugs engineered to meet factory performance, durability, and emissions expectations. Part number 3517 follows the original equipment style used on select Toyota engines, making it a practical choice for maintenance on the Toyota Corolla, Toyota Prius, Toyota Prius AWD-e, and Toyota Prius Prime. This part cross-references Denso Auto Parts FC16HR-CY9 and Toyota 90919-01281, 90919-01298 for the same application.

Common Issues This Part Can Address

• Rough idle caused by worn spark plug electrodes
• Hard starting from degraded ignition performance
• Misfire codes related to spark plug wear
• Reduced fuel economy from inconsistent combustion
• Loss of throttle response from aging plugs

Installation Notes and Tips

Verify engine application before installation and confirm the plug matches the specified thread diameter, reach, seat type, and heat range. Use proper spark plug service procedures, including checking the gap only if needed and tightening to the vehicle manufacturer’s torque specification. For Toyota Corolla, Prius, Prius AWD-e, and Prius Prime service, inspect ignition coils and plug wells during replacement to help ensure a clean repair.

Quality Assurance

Denso manufactures this spark plug to OE performance, durability, and emissions standards. The 3517 is built as an OE-style replacement for covered Toyota applications and is backed by Denso’s manufacturing standards for secondary ignition components.