Walker 350-35131 Oxygen Sensor - Upstream

OE Replacement Oxygen Sensor for BMW

Walker OE Replacement oxygen sensor 350-35131 is a specific-fit, upstream wide-band sensor engineered for BMW applications that require accurate air-fuel feedback to the ECU. It is built for direct replacement use on select BMW 320i, 328i, X3, and X5 models, with fitment matched to the listed bank and sensor position.

Key Features

• Wide-band oxygen sensor for precise exhaust feedback
• Heated design for faster operating temperature
• Specific-fit replacement for listed BMW applications
• Upstream mounting position for primary engine management input
• Threaded M18 x 1.5 mounting with 22 mm wrench size
• 5-wire, pin-terminal, rectangular-connector configuration
• Standard replacement grade for OE-style service

Product Details

Walker Products develops engine management and oxygen/air-fuel sensors as OE replacement parts for a wide range of vehicles. Part number 350-35131 is designed for upstream use where the ECU relies on sensor feedback to manage fuel delivery and emissions control. The sensor’s heated wide-band design supports stable signal output, while the specific connector, terminal, and thread configuration help ensure correct installation on the listed BMW models. Walker OE Replacement parts are backed by the company’s long-running focus on engine management components and ISO 9001/TS 16949 certified manufacturing practices.

This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Poor fuel economy caused by incorrect air-fuel feedback
• Rough running or hesitation from inaccurate sensor data
• Elevated exhaust emissions from a failing upstream sensor
• Fault codes stored in the ECU for sensor or related system issues

Installation Notes

• Verify the vehicle’s year, model, and upstream bank/sensor position before installation.
• Inspect the sensor wiring harness and connector for heat damage, corrosion, or broken terminals.
• Check the exhaust bung threads and mounting surface for contamination before threading in the sensor.
• Use the correct 22 mm wrench size and confirm the M18 x 1.5 thread specification.
• Clear stored fault codes after installation and confirm proper ECU feedback during a road test.

Quality Assurance

Walker Products manufactures this OE Replacement sensor as a standard replacement part for the listed BMW applications. The brand’s engine management catalog is built around application-specific fitment and diagnostic feedback requirements for modern ECU-controlled vehicles.