Walker 250-21010 Oxygen Sensor - Upstream

Walker OE Oxygen Sensor 250-21010

Walker Products OE 250-21010 is a specific-fit, threaded upstream oxygen sensor for vehicles that require direct ECU feedback from Bank 1 Sensor 1. It is built with a 1-wire, non-heated design and a radiused polygon female connector for the listed applications.

Key Features

• Specific-fit oxygen sensor for upstream Bank 1 Sensor 1 locations
• Non-heated sensor design with 1-wire configuration
• Threaded mounting type with 18.0 mm thread diameter
• 16.46 in. wiring harness length and 20-gauge wire
• Radiused polygon female connector for application-specific connection
• Walker Products OE line engineered as an OE-style replacement

Product Details

The Walker Products OE line focuses on application-specific engine management sensors for direct replacement use. Part number 250-21010 is designed for upstream oxygen sensor positions and is listed for 1990-1995 Ford, Kia, Mazda, and Mercury models, including the Ford Escort, Ford Festiva, Kia Sephia, Mazda 323, Mazda Protege, Mazda MX-3, and Mercury Tracer. For vehicles such as the Kia Sephia and Mazda 323, this upstream oxygen sensor supports the ECU with the feedback needed for fuel control and emissions monitoring.

Walker Products builds these sensors for the specified fitment position so the connector, harness length, and mounting style match the application. The 250-21010 part number is also referenced for Bank 1 Sensor 1 upstream oxygen sensor service on select vehicles, making it a practical choice when replacing a failed front oxygen sensor on the listed Ford Escort, Mazda Protege, or Mercury Tracer applications.

Common Reasons for Replacement

• Check engine light or malfunction indicator light related to oxygen sensor performance
• Poor engine operation caused by incorrect air-fuel feedback
• Increased fuel consumption from inaccurate sensor readings
• Higher exhaust emissions from a failing upstream sensor
• Stored ECU fault codes tied to the oxygen sensor circuit or related systems

Installation Notes

Confirm the vehicle uses the upstream Bank 1 Sensor 1 position before ordering. Inspect the sensor wiring harness and connector for damage, since physical wear can shorten service life and affect signal quality. Verify thread diameter, connector shape, and harness length against the original sensor before installation. This part is a threaded, specific-fit oxygen sensor and should be matched to the exact application listed for the vehicle.

Quality Assurance

Walker Products OE sensors are developed as original-equipment-style replacements for many global vehicle applications. The brand states its engine management and oxygen/air-fuel sensors are manufactured for specific fitment positions and diagnostic feedback requirements, with ISO 9001/TS 16949 manufacturing standards supporting product consistency.