Bosch 15445 Oxygen Sensor - Downstream Left

Bosch 15445 Oxygen Sensor Overview

Bosch 15445 is an Actual OE Oxygen Sensor built as a narrow-band heated replacement for precise air-fuel-ratio feedback to the ECU. It supports stable combustion control and emissions management for the 2001 INFINITI QX4, downstream left, early production.

As part of Bosch’s Actual OE Oxygen Sensor line, this sensor reflects Bosch’s long OE development history in switching-type O2 sensing, with a focus on accurate lambda measurement, faster closed-loop response, and dependable operation under heat and vibration.

Key Features

• Specific-fit oxygen sensor for the 2001 INFINITI QX4, downstream left
• Narrow-band heated sensor type for closed-loop fuel control
• 4-wire design with square connector and blade terminals
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Wiring harness included with 45.1 in harness length
• Metal housing and steel finish for underbody service conditions
• Bosch Actual OE Oxygen Sensor line for OE-style replacement performance

Detailed Description

Bosch 15445 is a direct-fit narrow-band heated oxygen sensor for the downstream left position on the 2001 INFINITI QX4, early production. It measures exhaust oxygen content and sends the signal the ECU uses to maintain the correct air-fuel ratio, helping the engine stay in closed-loop operation with consistent combustion control. The threaded sensor body, 4-wire configuration, and included harness support a clean replacement for the original sensor location.

Bosch’s Actual OE Oxygen Sensor line builds on the company’s OE sensor development, including switching-type and planar narrowband designs that improved response time and lambda accuracy. Bosch 15445 follows that OE-focused approach with ceramic sensing elements, controlled heater operation, and materials selected for high-temperature and vibration exposure. This part cross-references 226A14W004 for the same application.

What It Helps Address

• Check engine light caused by oxygen sensor signal faults
• Rich or lean fuel trim conditions from inaccurate exhaust feedback
• Slow closed-loop response during warm-up or steady cruising
• Emissions test failures related to sensor performance
• Rough combustion control from a worn downstream oxygen sensor

Installation Notes and Tips

Fits 2001 INFINITI QX4, downstream left. Confirm the early production application, connector shape, wire count, and threaded mounting before installation. Use the 18 mm hex size for removal and installation, and inspect the exhaust bung threads and harness routing so the sensor seats correctly and the lead is kept clear of heat sources.

Quality Assurance

Bosch supplies this Actual OE Oxygen Sensor as an OE-proven replacement backed by more than five decades of oxygen-sensor development and aftermarket support. The design reflects Bosch’s focus on accurate sensing, durable heater control, and reliable operation in demanding exhaust environments.