Bosch 17027 Oxygen Sensor - Downstream or Upstream

Bosch Actual OE Oxygen Sensor 17027

Bosch 17027 is a heated wideband air-fuel oxygen sensor built for precise exhaust feedback and stable engine management. It delivers continuous air-fuel ratio measurement across the full lambda range, helping the ECU maintain accurate mixture control in changing load and temperature conditions.

Compatible With 2014-2016 BMW 535d and 535d xDrive, plus 2015 BMW 740Ld xDrive, this Bosch Actual OE Oxygen Sensor supports downstream and upstream applications listed below. The 5-wire, specific-fit design includes a wiring harness and uses a threaded metal housing for OE-style replacement service.

Bosch Wideband A/F Sensor Line

Bosch pioneered the wideband oxygen sensor design used in modern engine management systems. This product line focuses on fast sensor response, controlled heater operation, and durable ceramic construction for consistent readings during rapid throttle changes and thermal cycling. Part number 17027 reflects that OE development background in an aftermarket replacement format.

Key Features

• Wideband A/F oxygen sensor for precise air-fuel ratio measurement
• Heated design for faster sensor activity and stable operation
• Specific-fit replacement with included wiring harness
• 5-wire configuration with blade terminals and oblong male connector
• Threaded mounting type with 18 mm thread diameter and 22 mm hex size
• Metal housing with standard replacement grade construction
• Overall length: 21.3 in; wire length: 21.3 in; harness length: 17.9 in

Detailed Description

Bosch 17027 is an Actual OE Oxygen Sensor engineered for vehicles that rely on wideband feedback for accurate fuel control. It measures exhaust oxygen content across the full lambda range, giving the ECU more detailed data than a traditional switching sensor. That level of signal precision supports cleaner combustion, steadier drivability, and more consistent emissions control.

This part number 17027 is listed for 2014-2016 BMW 535d, 2014-2016 BMW 535d xDrive, and 2015 BMW 740Ld xDrive in downstream and upstream positions as shown in the fitment data. If you are replacing a BMW 535d oxygen sensor or a BMW 740Ld xDrive oxygen sensor, this Bosch wideband unit matches the OE-style application requirements.

This part cross-references BMW 13627793825 for the same application.

What It Helps Address

• Fault codes related to oxygen sensor response or signal range
• Rough idle or inconsistent air-fuel mixture control
• Reduced fuel economy caused by inaccurate exhaust feedback
• Emissions test failures tied to sensor performance
• Delayed sensor activity after startup or during load changes

Installation Notes and Tips

Confirm the sensor position before ordering, since fitment includes both upstream and downstream applications. Inspect the connector shape, wire count, and thread size against the original sensor before installation. Use proper oxygen sensor service tools and follow the vehicle service procedure for routing, torque, and connector placement.

Quality Assurance

Bosch backs this oxygen sensor with more than five decades of OE development in engine management and emissions technology. The design uses robust ceramic construction, optimized heater control, and OE-proven sensor architecture for dependable replacement performance.