NTK 21045 Oxygen Sensor - Upstream

NTK 21045 Direct Fit Oxygen Sensor

NTK 21045 is a heated, direct fit oxygen sensor built for specific upstream applications. It is engineered with a 4-wire configuration, 18 mm threaded mounting, and a 9.75-inch wiring harness length for OE-style replacement on select Chevrolet, Saturn, Pontiac, and Oldsmobile vehicles.

As part of NTK’s Direct Fit Oxygen Sensor line, this sensor reflects the brand’s focus on OE application coverage, ceramic-based sensor manufacturing, and fit, form, and function that align with original equipment requirements.

Key Features

• Heated oxygen sensor for upstream exhaust monitoring
• Specific fit design for direct replacement installation
• 4-wire construction for the listed applications
• 18 mm threaded mounting type
• 9.75-inch wiring harness length
• OE-style replacement for select Bank 1 Sensor 1 locations

Application Details

Compatible with select 2002-2007 Chevrolet Cobalt, Cavalier, and Classic applications, as well as 2002-2007 Saturn Ion and Vue models, depending on engine and sensor position. It also covers select Pontiac Grand Am and Sunfire, Oldsmobile Alero, and Saturn L-series applications in the upstream Bank 1 Sensor 1 location. This part number, NTK 21045, is also listed for specific OE replacement use on these vehicles.

This part cross-references Bosch 15898 for the same application.

What This Sensor Helps Address

• Check engine light related to upstream oxygen sensor performance
• Incorrect air-fuel ratio feedback to the engine control module
• Reduced fuel control caused by a failing Bank 1 Sensor 1 signal
• Emissions test failures tied to oxygen sensor faults
• Slow or inaccurate sensor response in heated oxygen sensor circuits

Installation Notes and Tips

Verify the vehicle’s year, make, model, and upstream Bank 1 Sensor 1 location before ordering. Confirm the connector, thread size, and harness length match the original sensor on the vehicle. For best results, inspect the exhaust threads and wiring routing during replacement to ensure a secure installation.

Quality Assurance

NTK manufactures oxygen sensors with extensive testing during production to help ensure quality and reliability that meet or exceed OE specifications. The brand’s OE-focused sensor expertise supports direct-fit replacement for the listed Chevrolet Cobalt, Saturn Ion, and related applications.