Walker 250-25018 Oxygen Sensor

OE Oxygen Sensor for BMW and Mercedes-Benz

Walker Products OE oxygen sensor Part Number 250-25018 is a heated, specific-fit replacement built for upstream engine management feedback. It is engineered for vehicles that rely on precise air-fuel monitoring to maintain proper fuel control, emissions performance, and diagnostic accuracy.

Compatible With select 2006-2016 BMW and Mercedes-Benz applications, including BMW Z4, 328i, 335i, and Mercedes-Benz C250, SLK250, and C63 AMG upstream positions.

Key Features

• Heated oxygen sensor for faster operating response
• Specific-fit design for the listed upstream positions
• 5-wire configuration with male connector
• Threaded mounting with 18.0 mm thread diameter
• Wiring harness length: 57.6 in.
• Overall length: 61.14 in.
• Walker Products OE line replacement for application-specific fitment

Detailed Description

Walker Products OE Part Number 250-25018 is an upstream oxygen sensor designed to deliver the ECU feedback required for proper fuel-trim control and emissions monitoring. The Walker Products OE line focuses on application-specific replacements, with each part matched to the vehicle position and diagnostic needs of the original system. This sensor is built for threaded installation and uses a radiused polygon male connector with a 5-wire harness layout.

Fitment includes 2015-2016 BMW Z4 upstream front, 2006-2013 BMW 325i upstream, 2007-2013 BMW 328i upstream, 2007-2010 BMW 335i upstream, 2012-2015 Mercedes-Benz C250 upstream, and 2016 Mercedes-Benz C63 AMG upstream right or upstream left. Part number 250-25018 is also listed for additional BMW and Mercedes-Benz upstream applications across the 2006-2016 model years.

What This Sensor Helps Address

• Check engine light related to upstream oxygen sensor faults
• Rough engine operation caused by incorrect air-fuel feedback
• Increased fuel consumption from inaccurate sensor readings
• Elevated exhaust emissions from poor mixture control
• Stored ECU fault codes tied to Bank 1 Sensor 1 or upstream sensor positions

Installation Notes and Tips

Confirm the vehicle’s exact year, make, model, and sensor position before ordering. This part is a specific-fit, threaded oxygen sensor, so connector style, harness length, and mounting location should be matched to the original unit. Inspect the sensor wiring harness and connector for physical damage during diagnosis, since damaged wiring can shorten sensor life and affect readings.

For fitment reference, this part fits 2006-2011 BMW 525i, upstream; 2007-2010 BMW 335i, upstream; 2012-2015 Mercedes-Benz SLK250, upstream; and 2016 Mercedes-Benz C63 AMG, upstream left or upstream right, depending on application.

Quality Assurance

Walker Products has produced engine management and oxygen/air-fuel sensors since 1946 and operates as an ISO 9001 / TS 16949 certified company. The Walker Products OE line is developed as an original-equipment-style replacement for application-specific diagnostic performance.