Bosch 13439 Oxygen Sensor - Downstream

Bosch Actual OE Oxygen Sensor for Passat

Bosch 13439 is a specific-fit, narrow-band heated oxygen sensor built for precise air-fuel ratio feedback to the ECU. It is listed for the 1995 Volkswagen Passat, downstream, with notes for chassis # 3A..S..086 000 and Actual OE Oxygen Sensor application.

The Bosch Actual OE Oxygen Sensor line reflects Bosch’s long OE development history, including narrowband designs that improve closed-loop response, lambda accuracy, and heater performance under demanding exhaust temperatures. Bosch 13439 uses a threaded metal housing, 4-wire blade-terminal connector, and included wiring harness for a direct replacement style installation.

• Specific fit oxygen sensor for 1995 Volkswagen Passat, downstream
• Narrow-band heated sensor for stable closed-loop fuel control
• 4-wire design with rectangle male connector and blade terminals
• Threaded 18 mm sensor body with 22 mm hex size
• Wiring harness included; overall length 25.6 in
• Standard replacement grade for OE-style service work

Detailed Product Overview

Bosch 13439 is an emission control sensor that monitors exhaust oxygen content and sends accurate feedback to the engine control unit. That signal helps the ECU maintain the correct air-fuel mixture during normal driving, idle, and warm operating conditions. For Volkswagen Passat owners searching for a downstream oxygen sensor, Bosch 13439 provides the OE-style configuration and connector layout needed for the listed application.

This part cross-references Volkswagen 021906265N for the same application. Search terms such as 1995 Volkswagen Passat downstream oxygen sensor, Bosch 13439 oxygen sensor, and 1995 Passat narrow-band heated O2 sensor match this part’s fitment and design.

Common Issues This Sensor Addresses

• Fault codes related to downstream oxygen sensor performance
• Unstable fuel control caused by inaccurate exhaust oxygen readings
• Delayed closed-loop operation after warm-up
• Rough idle or drivability concerns tied to sensor signal degradation
• Emission test failures linked to a worn oxygen sensor

Installation Notes and Tips

Verify the vehicle is a 1995 Volkswagen Passat with the listed downstream location and chassis note before ordering. Use the 18 mm thread size and 22 mm hex specification to confirm tool fitment, and inspect the connector style, wire count, and harness length against the original sensor. Because this is a threaded exhaust sensor, proper removal technique and anti-seize practices should follow the vehicle service procedure.

Quality Assurance

Bosch supplies this Actual OE Oxygen Sensor as a standard replacement part backed by decades of OE sensor development. The design uses high-temperature-resistant materials, ceramic sensing elements, and controlled heater operation to support consistent performance in harsh exhaust conditions.