Bosch 15561 Oxygen Sensor - Downstream or Upstream

Bosch Oxygen Sensor for OE-Style Emissions Control

Bosch part 15561 is a specific-fit, narrow-band heated oxygen sensor built for precise air-fuel ratio feedback to the ECU. It supports stable combustion control and emissions management for select Chevrolet Aveo, Pontiac GTO, Pontiac Wave, and Pontiac Wave5 applications.

As part of the Bosch Engineered Oxygen Sensor line, this sensor reflects Bosch’s long OE development history in oxygen sensing, including narrowband designs that improve closed-loop response and lambda accuracy. Bosch 15561 is a threaded, heated sensor with a 4-wire harness and oblong male connector for direct replacement use.

Key Features

• Specific-fit oxygen sensor for select GM and Pontiac applications
• Narrow-band heated design for closed-loop fuel control
• 4-wire configuration with included wiring harness
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Metal housing with high-temperature-resistant construction
• Male oblong connector and blade terminals
• Standard replacement grade for emissions service work

Detailed Product Overview

Bosch 15561 is engineered as a switching-type oxygen sensor that reports exhaust oxygen content to the engine control unit so the system can adjust fuel delivery accurately. That feedback is important for maintaining stable combustion, reducing emissions, and keeping the engine in proper closed-loop operation. The heated narrow-band design helps the sensor reach operating temperature quickly and maintain consistent signal output under changing exhaust and thermal conditions.

This Bosch Engineered Oxygen Sensor is a direct replacement for vehicles that use a specific-fit, threaded O2 sensor with a 9.9-inch wiring harness length and 13.6-inch overall length. It is a practical choice for drivers and technicians servicing a 2004-2006 Chevrolet Aveo upstream sensor location or a 2004-2006 Pontiac GTO downstream sensor location. It also matches 2005 Pontiac Wave downstream and 2005 Pontiac Wave5 downstream applications. This part number 15561 is also referenced for OE-style service on these vehicles.

This part cross-references 19209818 and 96394003 for the same application.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Incorrect air-fuel ratio feedback to the ECU
• Slow closed-loop fuel control response
• Emissions test failures tied to sensor signal issues
• Rough combustion control caused by a worn upstream or downstream O2 sensor

Installation Notes and Tips

Confirm the sensor position before ordering, since Bosch 15561 is listed for both upstream and downstream locations depending on vehicle application. Verify the 18 mm thread size, 22 mm hex size, 4-wire connector style, and harness length against the original sensor before installation. Use proper oxygen sensor service tools and inspect the exhaust bung threads for damage or corrosion before threading in the replacement.

Quality Assurance

Bosch has more than five decades of OE oxygen sensor development behind this product line. The Bosch Engineered Oxygen Sensor range uses ceramic sensing elements, controlled heater operation, and heat-resistant materials to support consistent signal quality in demanding exhaust environments.