NTK 21518 Oxygen Sensor - Downstream Left

Direct Fit Oxygen Sensor for GM Applications

NTK oxygen sensor 21518 is a direct fit, specific-application replacement built for downstream left placement on select Chevrolet and GMC trucks and SUVs. It uses a heated, threaded design with a 4-wire configuration for straightforward OE-style service.

Key Features

• Direct fit oxygen sensor for specific applications
• Heated sensor design for faster operating response
• Threaded mounting with 18 mm thread diameter
• 21.75-inch wiring harness length
• 4-wire configuration
• NTK 21518

Detailed Description

NTK 21518 is part of the Direct Fit Oxygen Sensor line, which focuses on application-specific replacement parts with OE-style fit, form, and function. NTK is known for oxygen sensor manufacturing and uses ceramic technology developed from raw material through finished product control. This sensor is engineered for downstream left locations on 2001-2002 Chevrolet Silverado 2500 HD, Chevrolet Silverado 3500, Chevrolet Suburban 2500, GMC Sierra 2500 HD, GMC Sierra 3500, and related GM heavy-duty applications, plus the 2002 Chevrolet Avalanche 2500, Chevrolet C3500HD, GMC C3500HD, and GMC Yukon XL 2500.

NTK 21518 is extensively tested during manufacturing to meet or exceed OE specifications. This part cross-references Bosch 13701 and Delphi ES20097 for the same application.

What It Helps Address

• Faulty oxygen sensor readings
• Check engine light concerns related to sensor performance
• Slow sensor response from a worn heated element
• Incorrect air-fuel feedback in the exhaust system
• Fitment issues from using a universal sensor instead of a direct-fit part

Installation Notes and Tips

Compatible with specific GM downstream left applications only; verify the vehicle year, model, and position before ordering. The threaded mounting style and harness length are matched to the listed applications, and the 4-wire heated design supports OE-style replacement service. Use the vehicle's original routing and connector layout as a reference during installation.

Quality Assurance

NTK is the world's largest supplier and manufacturer of original equipment oxygen sensors. The 21518 is manufactured and tested to meet or exceed OE specifications for quality and reliability.