NTK 21543 Oxygen Sensor - Upstream, Upstream Left or Upstream Right

Direct Fit Oxygen Sensor for GM Trucks and Vans

NTK 21543 is a heated, direct fit oxygen sensor built for specific upstream applications on select Chevrolet and GMC trucks and vans. It is engineered for OE-style fit, form, and function, with the wiring length, threaded mounting, and 4-wire design needed for a clean replacement.

For owners searching for an oxygen sensor for Chevrolet Express 1500, GMC Savana 2500, or Chevrolet Tahoe upstream positions, NTK 21543 provides a direct replacement path without universal-fit guesswork.

Key Features

• Heated oxygen sensor for faster operating response
• Specific fit design for direct replacement
• 4-wire configuration
• 14.7500 wiring harness length
• 18.000 thread diameter with threaded mounting type
• OE-equivalent design for upstream right, upstream left, and upstream applications listed below

NTK Direct Fit Line Details

NTK’s Direct Fit Oxygen Sensor line is built around application-specific coverage for import and domestic vehicles. As part of the NGK family of products, NTK focuses on ceramic sensor technology and OE application support, with manufacturing controls that help maintain consistent sensor quality and reliable signal performance.

Part number 21543 is cross-referenced to Bosch 13027 and DENSO Auto Parts 234-4019 for the same application.

Detailed Description

NTK 21543 is a replacement oxygen sensor for select Chevrolet and GMC platforms from 1996 through 2002, including Chevrolet Express 1500, Express 2500, Express 3500, C2500, C3500, K2500, K3500, Silverado 2500, Suburban 2500, Tahoe, and GMC Savana, C-series, K-series, Sierra 2500, and Yukon XL 2500 applications. It is listed for upstream right, upstream left, and upstream positions depending on vehicle and engine configuration. If you are replacing a Chevrolet Express 3500 oxygen sensor or a GMC Savana 3500 upstream sensor, this part number is built for the specified OE-style location.

NTK 21543 is designed for direct fit installation on the listed vehicles and uses a heated sensor design to support proper exhaust feedback once the engine reaches operating temperature. The threaded mounting style and specific-fit construction help match the original sensor location and connector layout on the covered applications.

Common Problems This Part Can Address

• Check engine light related to oxygen sensor performance
• Rough idle or inconsistent air-fuel feedback from a worn sensor
• Reduced fuel economy caused by inaccurate exhaust readings
• Slow sensor response during warm-up on heated sensor applications
• Failed emissions inspection tied to a faulty upstream oxygen sensor

Installation Notes and Tips

Confirm the exact position before ordering, since this part is listed for upstream right, upstream left, and upstream locations across different Chevrolet and GMC applications. Match the connector, thread diameter, and harness length to the original sensor before installation. For best results, inspect the exhaust bung threads and wiring routing during replacement, especially on older GM trucks and vans where heat exposure can affect nearby components.

Quality Assurance

NTK is a major original equipment oxygen sensor supplier, and this sensor is manufactured and tested to meet or exceed OE specifications for the listed applications. The brand’s OE-focused engineering and ceramic sensor expertise support consistent fit and reliable operation on covered Chevrolet and GMC vehicles.