Walker 350-34337 Oxygen Sensor - Downstream

Walker 350-34337 Oxygen Sensor Overview

Walker Products 350-34337 is a heated oxygen sensor built as a specific-fit OE-style replacement for downstream applications. It is engineered to provide the ECU with the feedback needed for fuel control and emissions monitoring on select Subaru Forester and Subaru Impreza models.

Walker Products Aftermarket focuses on engine management and oxygen/air-fuel sensors for application-specific fitment. The 350-34337 follows the required mounting position, connector style, and wiring layout for the listed vehicles, helping maintain proper sensor signal performance in the exhaust system.

Key Features

• Heated oxygen sensor for downstream use
• Specific fit for the listed Subaru applications
• 4-wire design with 20-gauge wiring
• Radiused polygon male connector
• Threaded mounting with 18.0 mm thread diameter
• Wiring harness length: 15.87
• Overall length: 19.41

Fitment Details

• Fits 1999-2004 Subaru Forester, downstream.
• Fits 1999-2004 Subaru Impreza, downstream.
• Fits 1999 Subaru Impreza, downstream, B1S2 position for California emissions.
• Fits 1999 Subaru Impreza, downstream, B1S2 position for non-California vehicles.
• Fits 1999 Subaru Impreza, downstream, California-ESV vehicles in bank 1 sensor 2 position.
• Fits 1999 Subaru Impreza, downstream, non-California-ESV vehicles in bank 1 sensor 2 position.
• Fits 1999 Subaru Impreza, downstream, second bank sensor 1 position for non-California emissions.

What This Sensor Helps Address

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

Installation Notes

Confirm the downstream mounting position, connector shape, wire count, and thread diameter before installation. Inspect the sensor wiring harness and connector for heat damage, abrasion, or corrosion, since physical damage can shorten service life and affect signal quality. Verify the vehicle’s emissions configuration, especially on 1999 Subaru Impreza applications with California and non-California notes, before ordering.

Quality Assurance

Walker Products has supplied engine management components since 1946 and manufactures sensors for specific vehicle applications. The 350-34337 is produced to match the required fitment position and ECU feedback needs for the listed Subaru Forester and Subaru Impreza models.