NTK 21556 Oxygen Sensor

Direct Fit Oxygen Sensor for OE Replacement

NTK Direct Fit Oxygen Sensor 21556 is a heated, specific-fit replacement built for precise emissions monitoring and air/fuel feedback. It is engineered for vehicles such as the Chevrolet Equinox, GMC Terrain, and Buick LaCrosse, with OE-style fitment for upstream and downstream locations.

Key Features

• Heated oxygen sensor for faster operating response
• Specific-fit design for direct replacement installation
• 4-wire configuration with 20.5 in. wiring harness length
• 18 mm threaded mounting type
• OE-style fit, form, and function for emissions system service
• Extensively tested during manufacturing for quality and reliability

Product Line Details

NTK Direct Fit Oxygen Sensors are part of NTK’s OE-focused sensor line, developed under the NGK family of products. The brand uses ceramic manufacturing expertise and controlled production processes to support consistent sensor performance across import and domestic applications.

Detailed Description

Part number 21556 is a direct replacement oxygen sensor for a wide range of GM applications, including Chevrolet Equinox, GMC Terrain, Buick LaCrosse, Cadillac SRX, and Chevrolet Traverse. It is listed for upstream right, upstream left, downstream right, downstream left, and downstream positions depending on the vehicle, making it a fitment-focused solution for emissions repair and sensor replacement. This part cross-references Bosch 15130 and DENSO Auto Parts 234-4669 for the same application.

NTK manufactures oxygen sensors with OE application coverage in mind, and this heated sensor is built to match original equipment specifications for fit and function. If you are replacing a sensor on a 2010-2017 Chevrolet Equinox or 2010-2017 GMC Terrain, part 21556 provides a direct-fit option for the correct bank and sensor position when matched to the vehicle listing.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Incorrect air/fuel ratio feedback to the engine control system
• Slow sensor response from a worn heated O2 sensor
• Emissions test failures tied to sensor degradation
• Rough idle or drivability issues caused by inaccurate exhaust readings

Installation Notes and Tips

Verify the exact year, make, model, and sensor position before ordering. This sensor uses a threaded mounting type and a 4-wire heated design, so confirm connector routing and harness length against the original part. For vehicles such as the Buick Enclave, Chevrolet Impala, and Cadillac SRX, match the bank and sensor location carefully to the fitment listing.

Quality Assurance

NTK states that its oxygen sensors are tested during manufacturing to meet or exceed OE specifications. The brand’s OE manufacturing background and application coverage support consistent replacement quality for emissions control service.