Walker 350-34038 Oxygen Sensor - Upstream

Walker 350-34038 Oxygen Sensor for BMW 525i

Walker Products 350-34038 is a heated oxygen sensor built as a specific-fit replacement for select BMW applications. It is engineered for the upstream position on 1989-1992 BMW 525i models and is designed to provide the ECU with the feedback needed for fuel control and emissions monitoring.

Walker Products Aftermarket focuses on engine management and oxygen/air-fuel sensors for OE-style replacement use. For BMW 525i owners searching for an upstream oxygen sensor, part number 350-34038 offers application-specific fitment with the correct threaded mounting, connector style, and harness configuration.

Key Features

• Specific-fit oxygen sensor for select BMW 525i applications
• Heated sensor design for faster operating temperature
• Upstream position fitment for 1989-1992 BMW 525i
• 4-wire configuration with female connector
• Threaded mounting type with 18.0 mm thread diameter
• Wiring harness length: 27.09 in.
• Overall length: 30.63 in.
• Wire gauge: 20

Detailed Description

Walker 350-34038 is an oxygen sensor intended for vehicles that rely on upstream exhaust feedback to manage air-fuel ratio and emissions performance. This sensor is a direct-fit style replacement for the 1989-1992 BMW 525i, upstream, and is built to match the specified application rather than serving as a universal part. The heated design helps the sensor reach operating temperature more quickly, which supports earlier closed-loop operation after startup. If your BMW 525i is showing drivability concerns, elevated fuel use, or an emissions-related fault code, the oxygen sensor circuit is one of the first systems to inspect.

This part number, 350-34038, is part of Walker Products Aftermarket engine management coverage and is built around the vehicle-specific fitment requirements listed for the BMW 525i. This part cross-references Bosch (e.g., 13275) for the same application.

What It Helps Address

• Check engine light related to upstream oxygen sensor performance
• Rich or lean fuel mixture concerns
• Reduced fuel economy caused by inaccurate exhaust feedback
• Higher exhaust emissions from a failing sensor
• Poor engine operation during closed-loop fuel control

Installation Notes and Tips

Confirm the upstream location before installation and compare the connector, harness length, and thread size to the original sensor. Inspect the wiring harness and connector for heat damage, corrosion, or broken terminals before replacing the part. On the BMW 525i, a damaged sensor circuit can trigger ECU fault codes even when the sensor element is not the only issue. Use proper oxygen sensor service tools and verify the exhaust bung threads are clean before threading in the replacement sensor.

Quality Assurance

Walker Products states that its engine management sensors are developed as OE replacement parts for worldwide vehicle applications. The company is Automotive ISO9001/TS 16949 certified, and its sensor line is backed by long-running manufacturing experience dating to 1946.