Denso 5303 Spark Plug

Denso Iridium Power Spark Plug 5303

Denso Iridium Power 5303 is a performance spark plug built for precise ignition and stable combustion. It uses a 0.4 mm iridium center electrode, a tapered cut U-groove ground tip, and a 1.1 mm pre-gap to support consistent spark delivery in a wide range of import and domestic applications.

Key Features

• Iridium center electrode tip material for fine-wire ignition response
• World’s smallest 0.4 mm center electrode design for this product line
• Tapercut, U-groove ground electrode tip design
• 5000 ohm resistor for ignition noise suppression
• Copper core center electrode and nickel ground electrode core
• 14.00 mm thread diameter, 19.00 mm reach, flat seat
• 16.0 mm hex size and manufacturer heat range 16

Product Details

The Denso Iridium Power line focuses on compact electrode geometry and efficient spark exposure. On part number 5303, the fine iridium tip and tapered U-groove ground design help create a concentrated spark path, while the copper-core construction supports heat transfer. This spark plug is cross-referenced to Denso IK16 for the same application and is listed across a broad range of vehicles, including Mitsubishi Outlander Sport, Toyota Prius C, Toyota Yaris, and Mitsubishi Lancer applications.

Compatible fitment includes long-tail searches such as Denso 5303 spark plug for 2017-2022 Toyota Yaris, 2012-2018 Toyota Prius C, and 2017-2023 Mitsubishi Outlander Sport. It also appears in applications for Mitsubishi RVR, Scion xB, Hyundai Sonata, Kia Optima, Subaru Forester, and other vehicles shown in the fitment data.

Common Issues This Part Addresses

• Rough idle caused by worn or eroded spark plug electrodes
• Hard starting from weak or inconsistent spark output
• Misfire codes related to degraded ignition performance
• Reduced throttle response from inefficient combustion
• Ignition noise concerns in resistor-equipped systems

Installation Notes

Verify thread diameter, reach, seat type, and heat range before installation. Check the gap against the vehicle specification even though this plug is pre-gapped at 1.1 mm. Use the fitment notes carefully on vehicles that require special plug counts per cylinder, and confirm the exact engine application before ordering. For example, this part is listed for 2017-2022 Mitsubishi Outlander Sport, 2017-2018 Toyota Yaris, and 2012-2018 Toyota Prius C applications.

Quality Assurance

Denso manufactures the Iridium Power series with fine-wire iridium technology and application-specific engineering for ignition service. Part number 5303 is built to the published specifications above and should be matched to the vehicle’s required plug dimensions and heat range for proper service.