Bosch 15523 Oxygen Sensor - Downstream Left

Bosch Validated Oxygen Sensor for Downstream Left

Bosch Validated Oxygen Sensor 15523 is a specific-fit, narrow-band heated O2 sensor built for precise air-fuel-ratio feedback to the ECU. It supports stable combustion control and emissions management in applications such as the Infiniti G35, FX35, FX45, M35, M45, and Nissan 350Z.

Key Features

• Specific-fit Bosch Validated Oxygen Sensor for direct application matching
• Narrow-band heated oxygen sensor for closed-loop fuel control
• 4-wire design with blade terminals and square connector
• Threaded mounting with 18 mm thread size and 22 mm hex size
• Wiring harness included for a cleaner replacement setup
• Metal housing and high-temperature-resistant construction for demanding exhaust conditions
• Overall length: 15.7 in; harness length: 12.3 in

Detailed Description

Bosch part number 15523 uses the brand’s validated oxygen sensor design to deliver accurate switching-type signal output for downstream fuel and emissions control. Bosch’s oxygen sensor line evolved from its early OE development work and later planar narrowband designs, which improved light-off response, lambda accuracy, and closed-loop operation. This sensor is built with ceramic sensing elements and optimized heater control to maintain consistent performance under heat and vibration.

Compatible With 2003-2006 Infiniti G35, Downstream Left; 2003-2006 Infiniti FX35, Downstream Left; 2003-2008 Infiniti FX45, Downstream Left; 2006 Infiniti M35, Downstream Left; 2006-2010 Infiniti M45, Downstream Left; and 2003-2006 Nissan 350Z, Downstream Left. Bosch 15523 is a direct replacement choice for vehicles that need a narrow-band heated oxygen sensor in the downstream left position. This part cross-references 226A1AM601 for the same application.

What This Sensor Helps Address

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

Installation Notes and Tips

Verify the downstream left position, connector shape, wire count, and thread size before installation. Use the threaded mounting point and confirm the 18 mm sensor thread and 22 mm hex size match the original unit. Inspect the harness routing and connector orientation on Infiniti G35, FX35, FX45, M35, M45, and Nissan 350Z applications to ensure proper fitment.

Quality Assurance

Bosch brings more than five decades of OE oxygen sensor development to this replacement part. The Bosch Validated Oxygen Sensor line is built to OE-proven standards for accuracy, durability, and consistent signal performance in demanding exhaust environments.