NTK 21509 Oxygen Sensor - Downstream

Direct-fit oxygen sensor

The NTK 21509 is a specific-fit heated oxygen sensor built for downstream applications with threaded mounting and a 4-wire design. It uses a 23.7500-inch wiring harness and an 18.000 thread diameter for a direct-fit replacement approach.

Key features

• Heated oxygen sensor for faster operating response.
• Specific-fit design for direct replacement use.
• Threaded mounting with 18.000 thread diameter.
• 23.7500-inch wiring harness and 4-wire configuration.
• NTK 21509 direct-fit sensor line for OE-style coverage.

Detailed description

NTK 21509 is part of the Direct Fit Oxygen Sensor line, which focuses on application-specific coverage and OE-style fit, form, and function. NTK is part of the NGK family of products and is known for oxygen sensor manufacturing across import and domestic applications. This sensor is engineered for downstream use and is listed for Chevrolet Tracker, Suzuki Vitara, Suzuki Sidekick, Suzuki X-90, Geo Tracker, and Pontiac Sunrunner applications. The NTK 21509 is also cross-referenced to Bosch 13035 and Delphi ES20073 for the same application.

What it is used for

• Replacing a worn downstream oxygen sensor.
• Restoring proper sensor response in emission control systems.
• Addressing fault codes related to oxygen sensor performance.
• Correcting drivability issues tied to inaccurate exhaust feedback.
• Supporting emissions monitoring on listed Chevrolet Tracker and Suzuki applications.

Installation notes and tips

Verify the downstream location, threaded mounting style, wire count, and harness length before installation. Confirm the vehicle application by year, make, model, and emissions configuration, including Federal Emissions notes where listed. Use the part number 21509 to match the correct direct-fit oxygen sensor for the application.

Quality assurance

NTK states that its oxygen sensors are extensively tested during manufacturing and built to meet or exceed OE specifications. The 21509 reflects NTK's OE-focused sensor manufacturing approach and application coverage.