NTK 21550 Oxygen Sensor - Downstream

Direct-Fit Downstream Oxygen Sensor

NTK 21550 is a direct fit heated oxygen sensor built for specific vehicle applications and original equipment equivalent design. It is engineered for downstream placement on select Chevrolet, Pontiac, Buick, Oldsmobile, and Grand Am applications, including Chevrolet Cavalier and Pontiac Sunfire coverage.

Key Features

• Heated oxygen sensor for downstream exhaust monitoring
• Specific-fit design for direct replacement on listed applications
• 4-wire configuration with a 67.75-inch wiring harness
• Threaded mounting with 18 mm thread diameter
• Built to OE specifications for fit, form, and function
• Manufactured and tested for quality and reliability

Product Details

NTK 21550 is part of the Direct Fit Oxygen Sensor line, which focuses on application-specific replacement parts that match the original sensor layout and connection style. NTK draws on OE sensor manufacturing experience and ceramic technology to control key sensor components from raw material through finished production. This downstream oxygen sensor is listed for 1995-2002 Chevrolet Cavalier, 1995-2002 Pontiac Sunfire, 1996-1998 Buick Skylark, 1996-1998 Oldsmobile Achieva, 1998 Oldsmobile Cutlass, and 1996-1998 Pontiac Grand Am.

This part cross-references DENSO Auto Parts 234-4616 and Bosch 13450 for the same application.

Common Issues This Part May Address

• Check engine light related to downstream oxygen sensor performance
• Incorrect exhaust oxygen readings after sensor aging or contamination
• Slow sensor response affecting emissions monitoring
• Fault codes tied to heater circuit or sensor signal issues
• Failed emissions inspection caused by a worn oxygen sensor

Installation Notes and Tips

Verify the connector style, harness length, thread diameter, and downstream position before installation. This sensor uses a threaded mounting design and a 4-wire heated configuration, so matching the original vehicle setup is important for proper fitment. For best results, inspect the exhaust bung and wiring routing during replacement on Chevrolet Cavalier, Pontiac Sunfire, and other listed applications.

Quality Assurance

NTK oxygen sensors are manufactured and tested to meet or exceed OE specifications. As the Sensor Specialist within the NGK family of products, NTK supports import and domestic applications with OE-level coverage and application-specific sensor technology.