Walker 350-34478 Oxygen Sensor - Upstream, Upstream Left or Upstream Right

Walker 350-34478 Oxygen Sensor for Toyota

Walker Products 350-34478 is a heated, specific-fit oxygen sensor engineered as an OE-style replacement for select Toyota applications. It is built for upstream placement and provides the ECU with the feedback needed to manage fuel delivery and emissions control.

For Toyota 4Runner, Toyota Pickup, Toyota Land Cruiser, and Toyota MR2 applications, this sensor is matched to the listed position and connector style for direct replacement service. If your vehicle has a fault code, poor fuel economy, elevated emissions, or an illuminated MIL, the oxygen sensor circuit is one of the first systems to inspect.

Key Features

• Part number: 350-34478
• Heated oxygen sensor for faster operating response
• Specific fit for the listed Toyota applications
• Upstream placement for bank and sensor positions shown in fitment
• 4-wire design with female connector
• Radiused polygon connector shape
• 18.0 mm thread diameter
• Flange mount design
• Wiring harness length: 17.44
• Overall length: 20.98

Product Details

Walker Products Aftermarket focuses on engine management and oxygen/air-fuel sensors developed as replacement parts for a wide range of vehicles. This oxygen sensor is manufactured for the specific application and fitment position, helping restore the diagnostic feedback the ECU expects from the upstream sensor location. The 350-34478 is a practical choice when servicing Toyota emissions systems that rely on accurate exhaust-gas feedback for fuel control.

This part cross-references no listed interchange numbers in the provided data. For Toyota Pickup upstream oxygen sensor replacement, Toyota 4Runner upstream oxygen sensor service, or Toyota MR2 Bank 1 Sensor 1 replacement, use the fitment details below to confirm the correct position before ordering.

What It Helps Address

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

Installation Notes

• Confirm the vehicle year, model, and sensor position before installation.
• Inspect the sensor, wiring harness, and connector for physical damage before replacement.
• Verify the upstream location shown in the fitment data: Fits 1988-1989 Toyota Land Cruiser, upstream right; Fits 1988-1989 Toyota Land Cruiser, upstream left; Fits 1988-1989 Toyota MR2, upstream; Fits 1989-1991 Toyota Pickup, upstream; Fits 1990-1991 Toyota 4Runner, upstream.
• Use the listed connector and thread specifications to compare against the original part.

Quality Assurance

Walker Products has supplied engine management and fuel system components since 1946 and operates as an Automotive ISO9001/TS 16949 certified company. The 350-34478 is built to support the diagnostic feedback required by the ECU in the listed Toyota applications.