Bosch 13559 Oxygen Sensor - Upstream

Bosch OE Oxygen Sensor for BMW Upstream Applications

Bosch 13559 is an Actual OE Oxygen Sensor built for precise air-fuel-ratio feedback to the ECU. This narrow-band heated sensor supports stable combustion control and emissions management for select BMW upstream locations, including BMW 740i, 740iL, 318i, 318is, 318ti, 540i, Z3, and 840Ci applications.

Key Features

• Actual OE Oxygen Sensor from Bosch
• Narrow-band heated design for closed-loop operation
• Specific-fit sensor with round female connector
• 4-wire configuration with included wiring harness
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Metal housing built for high-temperature and vibration exposure
• Part number 13559 for direct catalog lookup

Product Details

Bosch 13559 uses a switching-type sensing element to measure oxygen content in the exhaust stream and send accurate feedback to the engine control unit. Bosch developed this sensor line from its original OE oxygen sensor technology and later planar narrowband designs, focusing on faster light-off, improved lambda accuracy, and quicker closed-loop response. For BMW upstream oxygen sensor replacement, this part number 13559 delivers the OE-style fit and signal behavior expected in emissions control service.

This part cross-references 11781247406 for the same application.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Rough idle caused by inaccurate air-fuel feedback
• Rich or lean fuel trim conditions
• Failed emissions inspection tied to upstream sensor output
• Delayed closed-loop fuel control after startup

Installation Notes and Tips

Install in the upstream exhaust position only where listed in the fitment data. Confirm the connector shape, 4-wire layout, and 18 mm thread size before installation. Inspect the harness routing and connector condition during replacement, and verify the exhaust bung threads are clean before threading the sensor into place.

• Fits 1997-2001 BMW 740i, Upstream
• Fits 1996-2001 BMW 740iL, Upstream
• Fits 1996-1999 BMW 318i, Upstream
• Fits 1996-1999 BMW 318is, Upstream
• Fits 1996-1999 BMW 318ti, Upstream
• Fits 1997-1998 BMW 540i, Upstream
• Fits 1996-1998 BMW Z3, Upstream
• Fits 1996-1997 BMW 840Ci, Upstream

Quality Assurance

Bosch backs this oxygen sensor with more than five decades of OE development experience. The sensor uses advanced ceramic elements, optimized heater control, and high-temperature-resistant materials to maintain consistent performance under thermal and vibration load. Bosch supplies this Actual OE Oxygen Sensor line to the aftermarket with OE-proven design standards.