Walker 350-34400 Oxygen Sensor - Upstream or Upstream Rear

Walker OE Replacement Oxygen Sensor for Ford Fiesta

Walker OE Replacement oxygen sensor 350-34400 is built for specific vehicle applications and provides the ECU feedback needed for proper fuel control and emissions monitoring. This heated, threaded sensor is a direct-fit style solution for 1998-2001 Ford Fiesta upstream applications.

Key Features

• Heated oxygen sensor for faster operating response
• Specific fitment for upstream placement
• Threaded mounting type with 18.0 mm thread diameter
• 4-wire design with 20-gauge wiring
• Wiring harness length: 5.83
• Overall length: 9.37
• Walker OE Replacement line for application-specific sensor coverage

Product Details

Walker Products engineers its engine management and oxygen/air-fuel sensors as OE replacement parts for defined vehicle applications. Part number 350-34400 is made for the upstream position on the Ford Fiesta and is intended to deliver the diagnostic feedback the ECU expects from the sensor circuit. The heated design helps the sensor reach operating temperature more quickly, which is important for accurate exhaust monitoring during normal driving.

The Walker OE Replacement line focuses on application-specific fitment, including sensor position, connector layout, and wiring configuration. For 1998-2001 Ford Fiesta upstream service, this sensor supports emissions system monitoring and fuel mixture control when the original sensor has aged or failed. If the sensor circuit is damaged, the wiring harness and connector should also be inspected for wear or physical damage.

What It Helps Address

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

Installation Notes and Tips

Confirm the upstream sensor location before ordering and match the threaded mounting style, wire count, and harness length to the original part. Inspect the connector and wiring for heat damage, corrosion, or abrasion before installation. A proper diagnosis should include the sensor circuit and related components, since wiring faults can shorten sensor life and trigger fault codes.

Quality Assurance

Walker Products states that its engine management and oxygen/air-fuel sensors are developed as OE replacement parts and manufactured for specific applications. The company is ISO 9001/TS 16949 certified and has supplied engine management and fuel system components since 1946.