Denso 5091 Spark Plug

Denso Double Platinum Spark Plug 5091

Denso Double Platinum 5091 is a spark plug built for OE-level ignition performance, durability, and emissions control. It is a direct-fit choice for a wide range of Ford, Mercury, Cadillac, Mercedes-Benz, Buick, Chevrolet, Pontiac, Oldsmobile, Mazda, and Lincoln applications, including popular Ford Ranger, Ford Escape, and Ford Fusion fitments.

Key Features

• Double Platinum design with a platinum chip ground electrode tip for stable spark performance
• Platinum center electrode tip with copper core for efficient ignition response
• Nickel ground electrode core material for dependable service life
• 5000 ohm resistance for proper ignition system operation
• Pre-gapped to 1.0 mm for OE-style setup
• Tapered seat, 14.00 mm thread diameter, 19.00 mm reach, and 16.0 mm hex size
• Manufactured to strict OE performance, durability, and emissions standards

Double Platinum Line Details

Denso Double Platinum plugs are built for applications that call for consistent ignition performance and long-term electrode stability. The platinum-on-platinum design helps maintain spark quality under everyday driving conditions, while the copper core supports efficient heat transfer. Part number 5091 is also referenced as Denso PT16EPR10 for cross-reference use.

Detailed Description

This Denso spark plug is engineered for vehicles that require a tapered-seat plug with a 14 mm thread and 19 mm reach. The 5000 ohm resistor helps control electrical noise, and the 1.0 mm pre-gap supports OE-style installation on the specified applications. It is a practical replacement for drivers servicing ignition systems on models such as the Ford Ranger, Ford Escape, and Ford Fusion, as well as many older domestic and European vehicles listed in the fitment data. This part cross-references Denso Auto Parts PT16EPR10 for the same application.

What It Helps Address

• Hard starting caused by worn or inconsistent spark plugs
• Rough idle from degraded ignition performance
• Misfire conditions related to electrode wear
• Reduced fuel economy from inefficient combustion
• Emissions issues tied to aging secondary ignition components

Installation Notes and Tips

Verify the engine calls for a tapered-seat, 14 mm spark plug with a 19.00 mm reach before installation. Confirm the gap specification against the vehicle service information, even though this plug is pre-gapped to 1.0 mm. Inspect ignition wires or coil-on-plug components during service, and torque the plug to the manufacturer’s specification to protect the threads and sealing surface.

Quality Assurance

Denso manufactures this plug to OE performance, durability, and emissions standards for consistent service in the listed applications. Part number 5091 is built as a direct replacement spark plug for vehicles that specify this design.