Walker 350-34684 Oxygen Sensor - Downstream or Downstream Left

Walker 350-34684 Oxygen Sensor Overview

Walker Products 350-34684 is a heated oxygen sensor built as a specific-fit OE replacement for select BMW applications. It is engineered to provide the ECU with the exhaust feedback needed for proper fuel control and emissions monitoring, making it a direct replacement choice for downstream sensor service on BMW M2, BMW M3, and BMW M4 models.

Walker Products Aftermarket focuses on engine management and oxygen/air-fuel sensors for application-specific fitment. The 350-34684 follows that approach with a threaded mounting design, 4-wire heated construction, and connector and harness dimensions matched to the listed vehicle positions.

Key Features

• Part number: 350-34684
• Heated oxygen sensor for downstream use
• Specific fitment for listed BMW applications
• 4-wire design with male connector
• Threaded mounting type with 18.0 mm thread diameter
• Wiring harness length: 23.42
• Overall length: 26.57
• Connector shape: radiused polygon

Detailed Description

This Walker oxygen sensor is intended for downstream exhaust monitoring on select BMW performance models, including BMW M2, BMW M3, and BMW M4 applications. It is listed for downstream left and downstream positions, including Bank 1 Sensor 2 service on covered vehicles. As an OE-style replacement sensor, it is built to deliver the diagnostic feedback the ECU expects for emissions and fuel-trim management.

Walker Products Aftermarket has supplied engine management components since 1946, and this sensor reflects that focus with application-specific fitment rather than universal coverage. If the original sensor has triggered a fault code, caused rough running, increased fuel consumption, or illuminated the malfunction indicator light, this replacement is designed for the same vehicle position and connector style.

Vehicle Fitment

• Fits 2021 BMW M2, downstream left.
• Fits 2019-2020 BMW M2, downstream left.
• Fits 2015-2020 BMW M4, downstream.
• Fits 2015-2018 BMW M3, downstream.

Common Issues This Sensor May Address

• Check engine light related to downstream oxygen sensor performance
• Stored ECU fault codes tied to Bank 1 Sensor 2
• Poor fuel economy caused by inaccurate exhaust feedback
• Elevated exhaust emissions from a failing heated oxygen sensor
• Rough engine operation associated with sensor signal loss

Installation Notes and Tips

Before replacement, inspect the sensor wiring harness and connector for heat damage, corrosion, or physical wear. Confirm the vehicle position, including downstream left or downstream Bank 1 Sensor 2 location, before installation. Verify thread diameter and connector style against the original part to ensure proper fit on the BMW M2, BMW M3, or BMW M4 application.

Quality Assurance

Walker Products manufactures engine management sensors as OE replacement components for specific applications and supports them through ISO 9001/TS 16949 certified operations. The 350-34684 is built to match the listed fitment and diagnostic requirements for the covered BMW applications.