NTK 21561 Oxygen Sensor - Upstream, Upstream Left or Upstream Right

Direct-fit oxygen sensor overview

The NTK 21561 is a direct-fit heated oxygen sensor built for specific applications that require OE-style fit, form, and function. It is engineered for upstream air/fuel ratio monitoring and uses a threaded mounting design with a 4-wire configuration.

Compatible With Chevrolet Colorado, GMC Canyon, and related applications, this sensor supports accurate exhaust feedback for vehicles that rely on precise mixture control. The NTK 21561 is part of the Direct Fit Oxygen Sensor line, which focuses on application-specific replacement coverage.

Key features

• Heated oxygen sensor for faster operating response
• Specific-fit design for direct replacement applications
• Threaded mounting type for OE-style installation
• 4-wire configuration for signal and heater circuit operation
• 19.7500-inch wiring harness length
• 18.000 thread diameter

Detailed application information

NTK 21561 is designed for upstream oxygen sensor locations across a wide range of GM and related vehicles, including Chevrolet Colorado, GMC Canyon, and Hummer H3 applications. Fitment also includes Cadillac STS, Chevrolet Trailblazer, GMC Envoy, Saab 9-7x, and several Isuzu models, with coverage that spans multiple model years and upstream positions. This part cross-references Bosch 15131 and Delphi ES20355 for the same application.

As part of NTK's Direct Fit Oxygen Sensor line, this sensor is built around application-specific coverage and OE-style replacement requirements. NTK's background as a major original equipment oxygen sensor supplier is reflected in the focus on fitment accuracy and manufacturing consistency. The 21561 part number is also referenced in interchange listings for related aftermarket and OE applications.

Common replacement concerns

• Faulty upstream oxygen sensor readings
• Check engine light related to air/fuel ratio monitoring
• Rough idle or drivability issues tied to mixture control
• Reduced fuel control accuracy from a worn heated sensor
• Direct-fit replacement needs for threaded sensor locations

Installation notes and quality assurance

Verify the connector style, thread diameter, harness length, and upstream position before installation. This sensor uses a threaded mounting type and a 4-wire heated design, so matching the original application details is important for proper operation.

NTK states that these oxygen sensors are extensively tested during manufacturing and are built to meet or exceed OE specifications. The 21561 is backed by that OE-focused manufacturing approach and application coverage.