NTK 21555 Oxygen Sensor

Direct Fit Oxygen Sensor for OE-Style Replacement

NTK 21555 is a direct fit heated oxygen sensor built for specific applications that require OE-style fit, form, and function. It is engineered for upstream and downstream positions across select Buick, Chevrolet, GMC, Cadillac, Pontiac, Saturn, and Saab vehicles, including Buick Regal, Chevrolet Equinox, and GMC Terrain applications.

Key Features

• Heated oxygen sensor with a specific-fit design
• 4-wire configuration for the listed applications
• Threaded mounting type with 18 mm thread diameter
• 21.75 in. wiring harness length
• OE-design replacement for upstream Bank 1 Sensor 1 and selected downstream positions
• Built by NTK, The Sensor Specialist, with ceramic control from raw material through finished sensor

Product Line Details

NTK Direct Fit Oxygen Sensors are part of the brand’s OE-focused sensor line. NTK uses manufacturing and testing processes developed around original equipment requirements, with coverage aimed at import and domestic vehicles that need accurate air/fuel ratio feedback and dependable emissions control performance.

Detailed Description

NTK 21555 oxygen sensor is designed for direct replacement in vehicles that call for a heated, threaded sensor with a specific connector and harness layout. It supports emissions system operation by monitoring exhaust oxygen content so the engine control system can maintain the proper air/fuel mixture. This part number is listed for a wide range of fitments, including 2011-2017 Buick Regal, 2012-2017 Buick Verano, 2015-2017 Chevrolet Equinox, and 2015-2017 GMC Terrain, along with additional applications such as Chevrolet Malibu, Chevrolet Impala, Cadillac SRX, and Chevrolet Silverado HD models. This part cross-references Bosch 15000 and DENSO Auto Parts 234-4257 for the same application.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Incorrect air/fuel ratio readings
• Rough idle or drivability issues tied to exhaust feedback
• Failed emissions inspection caused by sensor faults
• Slow sensor response in heated oxygen sensor circuits

Installation Notes and Tips

Verify the vehicle’s position, bank, and sensor location before ordering. Fits 2011-2017 Buick Regal, upstream; 2012-2017 Buick Verano, upstream; 2015-2017 Chevrolet Equinox, upstream; and 2015-2017 GMC Terrain, upstream. Additional listed applications include 2010-2016 Buick LaCrosse, 2009-2014 Chevrolet Malibu, 2014 Chevrolet Impala, 2007-2009 Cadillac SRX, and 2005-2013 Chevrolet Corvette in the specified upstream positions. Confirm connector style, thread size, and harness routing against the original sensor before installation.

Quality Assurance

NTK manufactures oxygen sensors to meet or exceed OE specifications and tests them during production for quality and reliability. As part of the NGK family of products, NTK focuses on OE application coverage and sensor technology for modern emissions systems.