Walker 250-21003 Oxygen Sensor - Upstream, Upstream Left or Upstream Right

Walker Products OE Oxygen Sensor 250-21003

Walker Products OE 250-21003 is a specific-fit oxygen sensor engineered as an OE-style replacement for select Ford, Mercury, and Lincoln applications. It is built for upstream placement and is designed to provide the ECU with the feedback needed for proper fuel control and emissions monitoring.

Key Features

• Specific-fit oxygen sensor for targeted vehicle applications
• Upstream placement for closed-loop fuel management feedback
• Non-heated sensor design with a threaded mounting type
• Female connector with radiused polygon connector shape
• 18.0 mm thread diameter, 7.99 in overall length, and 4.45 in wiring harness length
• 20-gauge wire with 1-wire construction
• Walker Products OE line engineered for original-equipment replacement needs

Product Details

This Walker Products oxygen sensor is part of the Walker Products OE line, a product line focused on original-equipment replacement fitment and application-specific sensor performance. Part number 250-21003 is intended for upstream locations on vehicles such as the Ford Mustang, Ford Ranger, Ford F-150, Mercury Cougar, and Lincoln Town Car, with fitment spanning model years from 1980 through 1991 depending on the application. It is a non-heated oxygen sensor that threads into the exhaust system and sends the ECU the exhaust feedback needed to manage air-fuel ratio and emissions strategy.

This part cross-references Standard Motor Products (e.g., SG8, SG12) for the same application.

Common Issues This Sensor May Address

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

Installation Notes and Tips

Verify the vehicle’s year, make, model, and sensor position before ordering. This sensor is listed for upstream use only, including upstream right and upstream left on the 1987 Mercury Cougar. Inspect the sensor wiring harness and connector for damage before installation, since damaged wiring can shorten sensor life and affect readings. Confirm the exhaust bung thread size and connector style match the vehicle before beginning service.

Quality Assurance

Walker Products has manufactured engine management and oxygen sensor components since 1946 and operates as an ISO 9001 / TS 16949 certified company. The 250-21003 is built as an OE replacement sensor for the listed applications and is backed by Walker Products’ application-focused manufacturing standards.