NTK 21004 Oxygen Sensor - Upstream

Direct Fit Oxygen Sensor for OE Replacement

The NTK Direct Fit Oxygen Sensor, part number 21004, is a heated, threaded upstream sensor built for specific-fit applications. It is engineered for direct replacement on select Chevrolet, GMC, Buick, Oldsmobile, and Pontiac vehicles, including 1993-1996 Chevrolet Lumina APV and 1995 Chevrolet Tahoe applications.

NTK is known for oxygen sensor coverage across import and domestic vehicles, with ceramic manufacturing expertise and OE-focused application support. This sensor is built to match original equipment fit, form, and function for the listed applications.

Key Features

• Heated oxygen sensor for upstream air/fuel ratio monitoring
• Specific-fit, threaded mounting design
• 3-wire configuration with 12.25 in. wiring harness length
• 18 mm thread diameter
• OE-style replacement from NTK, part number 21004
• Cross-references Bosch 15700 and DENSO Auto Parts 234-3011 for the same application

Product Details

NTK 21004 is a direct fit oxygen sensor for vehicles that use an upstream Bank 1 Sensor 1 location. It is listed for 1993 Buick LeSabre, Park Avenue, and Regal; 1993 Chevrolet Lumina APV; 1993 Oldsmobile 88, 98, and Silhouette; 1993 Pontiac Bonneville and Trans Sport; and 1995 Chevrolet and GMC full-size trucks, vans, and SUVs including C/K-series, G-series, Astro, Safari, Tahoe, and Yukon models. If you are searching for an oxygen sensor for a 1995 Chevrolet C1500 upstream or a 1995 GMC K2500 upstream, this part number 21004 is listed for those applications.

As part of NTK’s Direct Fit Oxygen Sensor line, this unit is intended to simplify replacement by matching the original sensor style used on the listed vehicles. NTK manufactures oxygen sensors with controlled ceramic technology and extensive testing to help meet OE specifications for fit and performance.

Common Reasons for Replacement

• Check engine light related to oxygen sensor performance
• Rough idle or inconsistent air/fuel ratio readings
• Reduced fuel economy from a failing upstream sensor
• Slow sensor response or aging heated sensor element
• Emission test failure tied to sensor output issues

Installation Notes and Tips

Confirm the vehicle’s year, make, model, and sensor position before ordering. This sensor is listed for upstream Bank 1 Sensor 1 locations on the applications shown, and it uses a threaded mounting style with a 3-wire heated design. Verify connector routing and harness length against the original sensor before installation. For best results, inspect the exhaust bung threads and wiring condition during replacement.

Quality Assurance

NTK is a major original equipment oxygen sensor supplier and manufacturer, and this Direct Fit Oxygen Sensor line is extensively tested during production to help meet or exceed OE specifications for quality and reliability.