Walker 350-34165 Oxygen Sensor - Upstream Front

Walker 350-34165 Oxygen Sensor Overview

Walker Products 350-34165 is a heated upstream front oxygen sensor built as a specific-fit OE replacement for select Mazda applications. It is engineered to deliver the ECU feedback needed for accurate air-fuel control in 2000-2002 Mazda 626 and 2001-2002 Mazda Millenia models.

Walker Products Aftermarket focuses on engine management and oxygen/air-fuel sensors for direct application fitment, and this sensor follows that approach with the correct threaded mounting, connector style, and harness length for the listed vehicles.

Key Features

• Specific-fit heated oxygen sensor for upstream front placement
• Threaded mounting type with 18.0 mm thread diameter
• 4-wire design with 20-gauge wiring
• Radiused polygon female connector for proper vehicle connection
• Wiring harness length: 21.18 in.; overall length: 24.72 in.
• OE-style replacement for Mazda 626 and Mazda Millenia applications

Detailed Description

The Walker Products 350-34165 oxygen sensor is designed for the upstream front exhaust location, where it monitors exhaust oxygen content and sends feedback to the engine control unit. That signal helps the ECU maintain the correct fuel mixture, which is important for drivability, emissions control, and fuel economy. This part number is listed for 2000 Mazda 626 California-ESV upstream front, as well as 2001-2002 Mazda 626 upstream front and 2001-2002 Mazda Millenia upstream front applications. If you are searching for a Mazda 626 upstream front oxygen sensor or a Mazda Millenia front oxygen sensor, Walker 350-34165 is the direct-fit option for those vehicles.

Walker Products Aftermarket builds engine management sensors as OE replacement components for specific applications, and part number 350-34165 is matched to the listed fitment and connector requirements. This part cross-references Bosch (e.g., 15733) for the same application.

What It Helps Address

• Check engine light related to upstream oxygen sensor performance
• Rough running caused by incorrect air-fuel feedback
• Increased fuel consumption from inaccurate sensor readings
• Elevated exhaust emissions from poor mixture control
• Fault codes stored in the ECU for the affected sensor circuit

Installation Notes

Confirm the sensor position before installation: this part is for the upstream front location only. Inspect the sensor wiring harness and connector for heat damage, abrasion, or corrosion before replacement, since physical damage can shorten sensor life and affect signal quality. Verify thread size, connector shape, and harness length against the original part before installation on your Mazda 626 or Mazda Millenia.

Quality Assurance

Walker Products states that its engine management sensors are developed as OE replacement parts and manufactured under Automotive ISO9001/TS 16949 quality systems. Since 1946, the brand has supplied engine management and fuel system components for a wide range of vehicle applications.