NTK 21049 Oxygen Sensor

Direct Fit Oxygen Sensor for OE Replacement

NTK 21049 is a direct fit heated oxygen sensor built for specific applications that require original equipment-style placement and signal performance. It is engineered for downstream and upstream positions across select Cadillac, Chevrolet, GMC, Hummer, Isuzu, and Oldsmobile vehicles, including Silverado 1500, Tahoe, and Trailblazer fitments.

As part of the NTK Direct Fit Oxygen Sensor line, this sensor is designed to streamline replacement selection while maintaining OE application coverage. NTK uses ceramic-based sensor manufacturing expertise and extensive production testing to deliver fit, form, and function aligned with original equipment specifications.

Key Features

• Heated oxygen sensor for faster operating temperature and stable signal output
• Specific-fit design for direct replacement in listed applications
• 4-wire configuration with a 16.75 in. wiring harness length
• Threaded mounting with 18 mm thread diameter
• OE-style replacement for downstream and upstream positions where listed
• Part number 21049 for catalog and cross-reference lookup

Product Details

NTK 21049 is built for drivers and technicians servicing emissions-related faults on GM and related platforms. It is listed for 2002-2007 vehicles including 2006-2007 Chevrolet Silverado 1500, 2006-2007 Chevrolet Tahoe, 2006-2007 GMC Sierra 1500, 2007 Cadillac Escalade, and 2002-2003 Chevrolet Trailblazer. This part number 21049 also covers additional downstream and upstream applications such as Chevrolet Avalanche, GMC Yukon, Hummer H2, and Isuzu Ascender.

This part cross-references Bosch 15898 and DENSO Auto Parts 234-4112 for the same application.

What This Sensor Helps Address

• Check engine lights related to oxygen sensor performance
• Incorrect air-fuel ratio readings from a worn sensor
• Slow sensor response during closed-loop operation
• Emissions test failures tied to sensor output issues
• Rough idle or drivability concerns caused by inaccurate exhaust feedback

Installation Notes and Tips

Verify the exact year, make, model, and sensor position before ordering. Fitment includes downstream right, downstream left, downstream, upstream right, and upstream positions depending on the vehicle. For example, it fits 2007 Chevrolet Silverado 1500 Classic, downstream right and downstream left; it fits 2006-2007 GMC Yukon, downstream right and downstream left; and it fits 2002-2003 Chevrolet Trailblazer, upstream.

Use the existing harness routing and connector orientation as a reference during replacement. Confirm thread engagement and sensor placement before final tightening to avoid exhaust leaks or signal issues.

Quality Assurance

NTK is a major original equipment oxygen sensor manufacturer, and this sensor is manufactured and tested to meet or exceed OE specifications for quality and reliability. The Direct Fit Oxygen Sensor line is supported by NTK’s OE application coverage and sensor engineering expertise.