NTK 21564 Oxygen Sensor - Downstream

Direct-Fit Downstream Oxygen Sensor

NTK oxygen sensor 21564 is a direct-fit, threaded replacement built for downstream applications with specific fitment. It uses a heated, 4-wire design and an 18 mm thread diameter for applications that require OE-style form and function.

Key Features

• Direct-fit oxygen sensor for specific applications
• Heated sensor design for faster operating response
• 4-wire configuration with 26.5 in. harness length
• Threaded mounting with 18 mm thread diameter
• Downstream fitment for select Chevrolet, Pontiac, and Saturn models

Detailed Description

NTK 21564 is part of the Direct Fit Oxygen Sensor line, which focuses on application-specific replacement sensors with OE-style fit, form, and function. NTK is known for oxygen sensor manufacturing and uses ceramic technology from raw material through finished production to maintain control over sensor quality. This part cross-references Bosch 15699 and DENSO Auto Parts 234-4245 for the same application. Fits 2008-2010 Chevrolet Cobalt, downstream; fits 2008-2010 Chevrolet HHR, downstream; fits 2009-2010 Saturn Sky, downstream; and fits 2009 Pontiac Solstice, downstream. It also fits 2007-2008 Pontiac Solstice, downstream, and 2007-2008 Saturn Sky, downstream, with B1S2 and 2nd design notes where listed. The part number 21564 is used across these direct-fit downstream applications.

What It Is Used For

• Replacing a worn or slow-responding downstream oxygen sensor
• Restoring accurate exhaust oxygen feedback to the engine management system
• Addressing sensor fault codes related to downstream monitoring
• Correcting drivability issues tied to aging emissions sensors
• Replacing a sensor with the wrong connector or thread specification

Installation Notes and Tips

Verify the vehicle year, model, and downstream position before ordering. Confirm the 4-wire layout, threaded mount, and 18 mm thread diameter match the original sensor. Some listed applications include a second-design note or sensor marking reference, so compare the original part number and connector details before installation. Use the part number 21564 to confirm the correct direct-fit application.

Quality Assurance

NTK states that these oxygen sensors are extensively tested during manufacturing and are built to meet or exceed OE specifications. The brand is part of the NGK family of products and supplies original equipment oxygen sensors globally.