NGK 3971 Spark Plug - Exhaust Side

NGK Laser Platinum Spark Plug 3971

NGK Laser Platinum Spark Plug 3971 is built for drivers who need OE-style ignition performance with a platinum center electrode and a nickel ground electrode. It is a direct-fit spark plug option for a wide range of import and domestic applications, including Toyota Corolla, Honda Accord, and Isuzu Rodeo fitments.

Key Features

• Laser Platinum design with a platinum center electrode tip for stable ignition performance
• Copper center electrode core for efficient conductivity
• Nickel ground electrode core with standard tip and standard configuration
• 5000 ohm resistance for ignition system compatibility
• Pre-gapped at .044 inches
• 14 mm thread diameter, .75 reach, flat seat, and 13/16 hex size
• NGK part number BPR5EP-11, stock number 3971

Product Details

NGK’s Laser Platinum Spark Plug line is built around OE replacement requirements, combining durable electrode materials with consistent gap control and reliable terminal design. Part number 3971 uses a platinum tip on the center electrode, a copper core for conductivity, and a nickel ground electrode to support steady spark delivery across a broad range of engine applications. This spark plug is listed for vehicles such as 1986-1989 Honda Accord, 1980-1988 Toyota Corolla, and 1991-1995 Isuzu Rodeo, with fitment notes that call for specific gap settings depending on the application.

This part cross-references Autolite APP64 for the same application.

Common Uses

• Restoring rough idle caused by worn spark plugs
• Addressing hard starting from weak or inconsistent spark
• Correcting misfire conditions tied to plug wear or improper gap
• Replacing plugs during scheduled ignition service on older Toyota, Honda, Isuzu, and Mazda vehicles
• Maintaining OE-style ignition performance in high-mileage engines

Installation Notes

Verify the specified gap before installation, since listed applications call for different settings such as 0.040, 0.042, 0.044, 0.045, or 0.050 inches depending on the vehicle. Use the correct torque procedure for the cylinder head material and confirm the flat seat style matches the engine specification. This NGK 3971 spark plug is listed across many applications, including Toyota Celica, Plymouth Voyager, and Mitsubishi 3000GT, so always match the vehicle year, engine, and OE gap requirement before service.

Quality Assurance

NGK is a major OE spark plug supplier in North America with more than 80 years of automotive manufacturing experience. The brand’s OE-focused production standards and broad vehicle coverage support consistent fitment and dependable ignition service across domestic and import applications.