NTK 21521 Oxygen Sensor - Downstream Left or Downstream Right

Direct Fit Oxygen Sensor

NTK 21521 is a direct fit heated oxygen sensor built for specific applications and engineered to match OE-style fit, form, and function. It is a threaded sensor with a 4-wire design and a 14.7500 wiring harness length for targeted replacement service.

• Heated oxygen sensor for precise exhaust feedback.
• Specific-fit design for direct replacement service.
• 4-wire configuration for application-matched connectivity.
• Threaded mounting with 18.000 thread diameter.

Application Details

Fits 1999-2001 Cadillac Catera, downstream right. Fits 1999-2001 Cadillac Catera, downstream left. This part cross-references Bosch 16063 and Delphi ES20108 for the same application. NTK 21521 is part of the Direct Fit Oxygen Sensor line, which focuses on application-specific coverage and OE-style replacement geometry for import and domestic vehicles.

What It Helps Address

• Faulty oxygen sensor readings that can trigger engine management concerns.
• Slow sensor response that can affect fuel control accuracy.
• Exhaust feedback issues related to a worn heated sensor.
• Replacement needs for a threaded, specific-fit sensor assembly.

Installation Notes

Use the listed fitment and position details to confirm the correct downstream side before installation. Verify connector style, thread diameter, and harness length against the original sensor on the vehicle. Because this is a specific-fit oxygen sensor, it is intended for direct replacement on the listed Cadillac Catera applications.

Quality Assurance

NTK is a major original equipment oxygen sensor supplier and manufacturer. Each sensor is extensively tested during production to help ensure quality and reliability that meet or exceed OE specifications.