Denso 3173 Spark Plug

Denso Double Platinum Spark Plug 3173

Denso Double Platinum Spark Plug 3173 is built for OE-level ignition performance, durability, and emissions control. It uses a platinum chip ground electrode, a platinum center electrode tip, and a copper core to support consistent spark delivery in demanding daily driving conditions.

Key Features

• Double Platinum design with platinum on the center electrode tip and platinum chip ground electrode tip
• 5000 ohm resistor helps control electrical noise in the ignition system
• Standard ground configuration with a single ground electrode
• Copper center electrode core for efficient heat transfer
• Nickel ground electrode core material for stable operation
• Pre-gapped to 0.8 mm for OE-style setup
• 14.00 mm thread diameter, 19.00 mm reach, 16.0 mm hex size, flat seat

Product Details

Denso Double Platinum 3173 is engineered to meet strict OE performance, durability, and emissions standards. The Double Platinum construction helps maintain spark consistency over time, while the resistor design supports cleaner ignition system operation. This spark plug is a direct-fit style replacement for select Mazda and Dodge applications, including Mazda Protege, Mazda 626, Mazda Millenia, and Dodge Caliber models listed in the fitment data. For shoppers searching for a Mazda 626 spark plug, Mazda Millenia ignition tune-up part, or Dodge Caliber Double Platinum spark plug, part number 3173 is the relevant reference.

This part cross-references DENSO Auto Parts PKJ20CR8 for the same application.

Common Issues This Part Can Address

• Rough idle caused by worn spark plug electrodes
• Hard starting from weakened ignition output
• Misfire conditions related to aged plugs
• Reduced fuel economy from inconsistent spark delivery
• Emissions concerns tied to degraded ignition performance

Installation Notes and Tips

Verify thread diameter, reach, seat type, and heat range before installation. Use the listed 0.8 mm pre-gap as the starting point and confirm the engine specification for your application. Inspect ignition coils, wires, and boots during service so the new plug can perform as intended. Confirm vehicle-specific fitment for 2008-2009 Dodge Caliber, 2003 Mazda Protege, 1998-2002 Mazda 626, and 1995-2002 Mazda Millenia before ordering.

Quality Assurance

Denso manufactures this spark plug to OE performance, durability, and emissions standards. The Double Platinum line is designed for consistent ignition service in factory-style applications, including Mazda Protege, Mazda 626, and Mazda Millenia models covered by the fitment data.