Bosch 15109 Oxygen Sensor - Downstream

Bosch Actual OE Oxygen Sensor for BMW and Land Rover

Bosch Part Number 15109 is an Actual OE Oxygen Sensor built for downstream air-fuel monitoring on select BMW and Land Rover applications. It uses a narrow-band heated design with a 4-wire harness, threaded mounting, and OE-style connector layout to deliver stable signal feedback to the ECU.

For drivers searching for a downstream oxygen sensor for BMW X3, BMW X5, or BMW 330i applications, Bosch 15109 provides the OE-level fit and sensor response expected from Bosch’s long history in oxygen sensor development.

Key Features

• Actual OE Oxygen Sensor from Bosch’s OE-focused product line
• Narrow-band heated sensor for closed-loop fuel control
• Specific fit design with round male connector and blade terminals
• Threaded 18 mm mounting with 22 mm hex size
• Wiring harness included for direct replacement routing
• Built with high-temperature-resistant materials for demanding exhaust conditions
• Part number 15109 for easy identification and ordering

Product Details

Bosch 15109 is a switching-type oxygen sensor that measures exhaust oxygen content and sends precise feedback to the ECU so the engine can maintain stable combustion control and emissions performance. Bosch’s narrow-band sensor design uses advanced ceramic elements and controlled heater operation to support faster light-off and quicker closed-loop operation after startup. This makes it a practical replacement for downstream sensor service on BMW X3, BMW X5, BMW 525i, BMW 530i, and Land Rover Range Rover applications listed in the fitment data.

This part cross-references Bosch-style OE applications such as 11781433940 and MHK000220 for the same application.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Unstable air-fuel ratio feedback from a worn downstream sensor
• Slow sensor response during closed-loop operation
• Emissions test failures tied to exhaust monitoring faults
• Rough combustion control caused by inaccurate lambda readings

Installation Notes and Tips

Install Bosch 15109 in the downstream exhaust position only where listed in the fitment data. Verify connector shape, wire count, thread size, and harness length before installation. Because this is a threaded oxygen sensor, use the correct oxygen sensor socket and apply proper anti-seize practices only if approved for the application and sensor design. Confirm the vehicle build date on 2003 BMW 325Ci, 325i, 330Ci, and 330i applications noted as to 02/2003.

Compatible With 1999-2002 BMW Z3, Downstream; 2001-2006 BMW X5, Downstream; 2004-2006 BMW X3, Downstream; 2003-2005 BMW Z4, Downstream; 2003-2005 Land Rover Range Rover, Downstream; and additional BMW 3 Series, 5 Series, and 528i applications listed in the fitment data.

Quality Assurance

Bosch has more than five decades of oxygen sensor OE development, and this Actual OE Oxygen Sensor reflects that experience with OE-proven materials, heater control, and sensor architecture. Bosch 15109 is engineered for consistent signal accuracy and durable operation in high-heat, high-vibration exhaust environments.