Walker 350-34278 Oxygen Sensor - Downstream, Downstream Front or Downstream Rear

Walker 350-34278 Oxygen Sensor for Mazda and Ford

Walker Products 350-34278 is a heated oxygen sensor built as a specific-fit OE-style replacement for select Mazda and Ford applications. It is engineered for the correct mounting position and ECU feedback on downstream front, downstream, and downstream rear locations.

Key Features

• Heated oxygen sensor for emissions and fuel-control feedback
• Specific fitment for the listed vehicle applications
• 4-wire design with female connector
• Threaded mounting type with 18.0 mm thread diameter
• Wiring harness length: 23.15 in.; overall length: 26.69 in.
• Radiused polygon connector shape for application-specific connection

Product Details

Walker Products Aftermarket focuses on engine management and oxygen/air-fuel sensors engineered for direct replacement use. Part number 350-34278 is designed for the correct sensor location and signal response required by the ECU, helping maintain proper emissions-system operation on vehicles such as the Mazda Millenia, Mazda 626, Mazda MX-6, and Ford Probe. This sensor line is built around application-specific fitment rather than universal coverage, which is important when replacing a downstream oxygen sensor on vehicles with exact connector and harness requirements.

This part cross-references no listed alternate part numbers in the provided data.

Vehicle Fitment

• Fits 1995-2002 Mazda Millenia, Downstream Front
• Fits 1995-1996 Mazda Millenia, Downstream Rear
• Fits 1997-1999 Mazda 626, Downstream Front
• Fits 1998-1999 Mazda 626, Downstream
• Fits 2000 Mazda 626, Downstream Front
• Fits 1997 Mazda MX-6, Downstream Front
• Fits 1997 Ford Probe, Downstream Rear

What It Helps Address

• Check engine light related to oxygen sensor performance
• Poor engine operation caused by incorrect exhaust feedback
• Increased fuel consumption from inaccurate air-fuel monitoring
• Higher exhaust emissions from a failing heated oxygen sensor
• Fault codes stored in the ECU for the affected sensor circuit

Installation Notes

Verify the sensor position before installation, since this part is listed for downstream front, downstream, and downstream rear applications depending on vehicle and engine configuration. Inspect the wiring harness and connector for damage before replacement, and confirm the threaded mounting location matches the original sensor. For best results, compare the connector shape, wire count, and harness length to the removed part before installation.

Quality Assurance

Walker Products manufactures engine management sensors as OE-replacement parts for specific applications and builds them under Automotive ISO9001/TS 16949 quality systems. The brand has supplied fuel system and sensor components since 1946, with application-focused cataloging and fitment control for modern emissions systems.