NTK 21071 Oxygen Sensor - Downstream

Direct Fit Oxygen Sensor for OE Replacement

The NTK Direct Fit Oxygen Sensor 21071 is a heated, specific-fit downstream sensor built for precise replacement in select Chevrolet, Buick, and GMC applications. It is engineered with a 4-wire layout, threaded mounting, and an 18 mm thread diameter for OE-style service on vehicles such as the Chevrolet Malibu, Chevrolet Blazer, and GMC Acadia.

NTK is the Sensor Specialist within the NGK family, and this oxygen sensor line is built around controlled ceramic manufacturing and OE application coverage. The result is a direct-fit replacement that matches original sensor form, fit, and function for downstream monitoring.

Key Features

• Direct fit oxygen sensor for specific vehicle applications
• Heated sensor design for downstream exhaust monitoring
• 4-wire configuration with 14.75 in. wiring harness length
• Threaded mounting with 18 mm thread diameter
• OE-style replacement for select Buick, Chevrolet, and GMC models
• Cross-reference: this part cross-references 12661898 for the same application

Detailed Description

NTK part number 21071 is a downstream oxygen sensor designed for vehicles that require a specific-fit replacement rather than a universal sensor. It is listed for applications including 2013-2020 Chevrolet Malibu, 2018-2020 Chevrolet Equinox, 2017-2020 GMC Acadia, and 2016-2020 Buick Envision, along with additional Buick, Chevrolet, and GMC models. For buyers searching for a downstream oxygen sensor for Chevrolet Malibu or a direct fit oxygen sensor for GMC Acadia, this part provides an OE-style service solution.

NTK manufactures oxygen sensors with attention to ceramic control, fitment accuracy, and OE specification alignment. Part number 21071 is intended for downstream positions and supports emissions system monitoring on the listed vehicles. If you are replacing a worn sensor on a Chevrolet Blazer, Buick Regal, or GMC Terrain, this NTK sensor is built to match the original application requirements.

What It Helps Address

• Check engine light related to downstream oxygen sensor performance
• Fault codes tied to air-fuel ratio or catalyst monitoring
• Rough emissions readings from a degraded sensor
• Slow sensor response caused by age or contamination
• OE replacement needs for listed Chevrolet, Buick, and GMC models

Installation Notes and Tips

Confirm the vehicle’s year, make, model, and downstream sensor position before ordering. This is a specific-fit, threaded oxygen sensor with a 4-wire connector layout, so connector style and harness routing should be matched to the original part. Verify the application against the vehicle’s emissions configuration, especially on models such as the Chevrolet Malibu, Chevrolet Blazer, and GMC Acadia.

Quality Assurance

NTK builds oxygen sensors using OE-focused manufacturing methods and tests them during production to support quality and reliability that meet or exceed original equipment specifications. The 21071 is part of NTK’s direct-fit oxygen sensor line for import and domestic coverage.