Denso 5371 Spark Plug

Denso Iridium Power Spark Plug 5371

Denso Iridium Power spark plug 5371 is built for drivers who want precise ignition performance from a compact iridium design. It uses a 0.4 mm iridium center electrode to support consistent spark delivery, along with a tapercut and U-groove ground electrode profile for efficient flame initiation.

For Honda Civic and Toyota Corolla service applications, Denso 5371 is a direct-fit style spark plug with a 12.0 mm thread diameter, 19.00 mm reach, flat seat, and 18.0 mm hex size. The 5000 ohm resistor design helps control electrical noise in modern ignition systems.

Key Features

• Iridium center electrode with 0.4 mm tip for focused spark delivery
• Tapercut, U-groove ground electrode tip design
• 5000 ohm resistor construction
• Copper core center electrode and nickel ground electrode core
• Pre-gapped to 0.8 mm
• Flat seat, 12.00 mm thread diameter, 19.00 mm reach, 18.0 mm hex size
• Denso Iridium Power line for performance-oriented ignition service

Detailed Description

Denso Iridium Power 5371 is engineered as a secondary ignition spark plug that combines an iridium center electrode with a copper core for stable conductivity and a durable firing tip. The small-diameter iridium center electrode reduces the required firing voltage, while the tapercut and U-groove ground electrode shape supports a concentrated spark path. This part cross-references DENSO Auto Parts IX22 for the same application. Use Denso 5371 when servicing ignition systems on vehicles such as Honda Civic and Toyota Corolla where the specified thread, reach, seat type, and heat range match the original application requirements.

What It Helps Address

• Hard starting caused by worn spark plug electrodes
• Rough idle from inconsistent ignition firing
• Misfire conditions related to plug wear or excessive gap growth
• Reduced throttle response from weak spark delivery
• Ignition noise control needs in resistor-equipped systems

Installation Notes and Tips

Verify thread diameter, reach, seat type, heat range, and hex size before installation. Confirm the pre-gap specification against the vehicle service information and inspect the ignition coil, boots, and plug wells for contamination or damage during service. For Honda Civic and Toyota Corolla maintenance, match the plug specification to the engine application rather than relying on model name alone.

Quality Assurance

Denso Iridium Power plugs are built around a fine-wire iridium center electrode for precise ignition performance and consistent service characteristics. Part number 5371 is manufactured to the listed specifications for fitment-critical ignition replacement.