Bosch 13052 Oxygen Sensor - Upstream

Bosch Actual OE Oxygen Sensor 13052

Bosch 13052 is a specific-fit, narrow-band heated oxygen sensor built for upstream applications where accurate air-fuel ratio feedback is critical. It uses a threaded metal housing, a round female connector, and a 4-wire harness to deliver stable signal response across changing exhaust temperatures.

Compatible with select BMW applications, including 1988-1993 BMW 535i, 1988-1989 BMW 535is, 1991-1993 BMW M5, 1988-1992 BMW 735i, 1988-1992 BMW 735iL, and 1988-1992 BMW 635CSi in the upstream position. This part number, 13052, is an OE-style replacement for vehicles that require the listed connector and harness length.

Key Features

• Actual OE Oxygen Sensor from Bosch
• Narrow-band heated oxygen sensor for upstream exhaust monitoring
• Specific fit with included wiring harness
• 4-wire design with pin terminals and round female connector
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Metal housing for high-temperature and vibration exposure
• Wiring harness length: 56.1 in; overall length: 59.8 in

Product Details

Bosch developed its oxygen sensor technology from early OE designs and later narrowband planar sensor architecture to improve light-off response, lambda accuracy, and closed-loop operation. Bosch 13052 follows that OE development path with a heated sensing element and optimized heater control for consistent signal output during warm-up and normal driving. For BMW 535i, M5, 735i, 735iL, and 635CSi applications, this sensor supports the ECU’s fuel-control strategy by reporting exhaust oxygen content in the upstream location.

This part cross-references 11781720537 for the same application.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Rough idle caused by inaccurate air-fuel feedback
• Fuel mixture correction issues during closed-loop operation
• Slow sensor response after cold start
• Emissions test failures tied to upstream sensor faults

Installation Notes

Install in the upstream exhaust location only where the vehicle calls for this Bosch configuration. Verify connector shape, terminal count, harness length, and thread size before installation. Use the 18 mm thread specification and 22 mm hex size to match the correct service tool, and confirm the sensor seats cleanly in the threaded bung without forcing the connector.

Quality Assurance

Bosch backs this oxygen sensor with more than five decades of OE sensor development and aftermarket supply experience. The design uses durable ceramic sensing elements, heater control, and high-temperature-resistant materials to maintain stable operation under thermal and vibration load.