Bosch 15321 Oxygen Sensor - Downstream, Downstream Left or Upstream

Overview of Bosch Actual OE Oxygen Sensor 15321

The Bosch Actual OE Oxygen Sensor 15321 is designed specifically for select BMW models, including the 545i, 645Ci, 745i, and 745Li. This narrow-band heated oxygen sensor ensures accurate emissions control and optimal engine performance by providing precise air-fuel mixture data to the vehicle's engine management system.

• Specific fit for BMW 545i, 645Ci, 745i, and 745Li models
• Heated narrow-band oxygen sensor for reliable operation
• Threaded mounting type with 18 mm thread diameter and 22 mm hex size
• Includes a 14-inch wiring harness with 4 wires and male blade terminals
• Durable metal housing finished in steel for long-lasting use
• Connector is round and male with 4 terminals for secure connection
• Overall length of 17.7 inches with 16.5 inches from sealing surface to connector end

Detailed Product Description

The Bosch Actual OE Oxygen Sensor 15321 is engineered as a standard replacement part that matches the original equipment specifications for BMW vehicles. Featuring a heated narrow-band sensor type, it quickly reaches operating temperature to provide accurate oxygen level readings. The sensor’s metal housing and steel finish contribute to its durability under harsh engine conditions. The threaded mounting type with an 18 mm diameter and 22 mm hex size allows for straightforward installation using common tools. The included wiring harness measures 14 inches and contains four wires with male blade terminals, ensuring a secure and reliable electrical connection. This sensor is designed specifically for BMW 545i, 645Ci, 745i, and 745Li models, making it a precise fit for these vehicles.

About the Bosch Actual OE Oxygen Sensor Product Line

The Actual OE Oxygen Sensor line by Bosch focuses on delivering direct replacement sensors that meet original equipment standards. This product line emphasizes compatibility and performance, ensuring that each sensor integrates seamlessly with the vehicle’s emission control system. The 15321 sensor is part of this line, providing BMW owners with a reliable option that maintains factory-level emissions accuracy and engine efficiency.

Common Applications and Issues Addressed

• Restores accurate air-fuel ratio readings for improved engine performance
• Resolves check engine light triggers related to oxygen sensor faults
• Helps reduce vehicle emissions by ensuring proper sensor function
• Prevents poor fuel economy caused by faulty oxygen sensors
• Eliminates rough idling or engine hesitation linked to sensor failure

Installation Notes and Tips

Installation of the Bosch 15321 oxygen sensor requires a 22 mm hex socket for the threaded mounting. Ensure the engine is cool before removal to avoid burns. The sensor’s wiring harness includes four wires with male blade terminals and a round male connector, so verify connector compatibility before installation. No mounting bracket is included, so use the existing mounting point on the vehicle. Proper torque specifications should be followed to avoid sensor damage or exhaust leaks.

Quality Assurance and Warranty

Bosch oxygen sensors are manufactured to meet strict quality standards, ensuring reliable performance and durability. The Actual OE Oxygen Sensor 15321 undergoes rigorous testing to comply with OEM specifications. While specific warranty details are not provided here, Bosch typically offers limited warranties on their emission control sensors to cover defects in materials and workmanship.