Denso 5381 Spark Plug

Denso Iridium Power Spark Plug 5381

Denso Iridium Power 5381 is a performance spark plug built for precise ignition response and stable combustion. It uses a 0.4 mm iridium center electrode, a copper core center electrode, and a nickel ground electrode to support consistent spark delivery in demanding street and performance use.

For drivers searching for a Denso spark plug for Honda Civic or Toyota Corolla ignition service, this Iridium Power design focuses on efficient firing and dependable electrical characteristics. The 5381 part number is also referenced as DENSO Auto Parts IWF27.

Key Features

• Iridium center electrode tip with a 0.4 mm fine-wire design
• Tapercut and U-groove ground electrode tip design for focused spark exposure
• 5000 ohm resistor for ignition noise suppression
• Flat seat, 14.00 mm thread diameter, and 12.70 mm reach
• 0.8 pre-gap size for OE-style setup consistency
• 20.6 mm hex size for standard service tool access
• Manufacturer heat range 27 for specified thermal control

Product Details

The Iridium Power line is Denso’s performance-focused spark plug family, and this plug is engineered around a small-diameter iridium center electrode to improve spark concentration. The copper core center electrode helps manage heat transfer, while the nickel ground electrode and single-ground configuration support durable operation. The 5381 spark plug is a direct choice for buyers comparing Denso 5381 against IWF27 for ignition maintenance and performance tuning.

With its flat seat, standard ground configuration, and 14 mm thread size, this spark plug is built for applications that call for a compact, fine-wire iridium plug. It is a practical option for ignition service on vehicles such as Honda Civic and Toyota Corolla when the specified plug dimensions and heat range match the engine requirements.

Common Issues This Spark Plug Can Address

• Rough idle caused by worn or inconsistent spark plugs
• Hard starting from weak ignition output
• Misfire symptoms related to degraded plug electrodes
• Reduced throttle response from inefficient combustion
• Ignition noise concerns where resistor plugs are specified

Installation Notes and Tips

Verify the required thread diameter, reach, seat type, heat range, and pre-gap before installation. Use the engine manufacturer’s specified torque procedure and confirm the gap setting matches the application requirements. For Honda Civic and Toyota Corolla service, compare the original plug specification carefully before replacing the existing plug with Denso 5381.

Quality Assurance

Denso Iridium Power plugs are built around a fine-wire iridium center electrode and OE-style dimensional specifications for controlled ignition performance. This part cross-references DENSO Auto Parts IWF27 for the same application.