Bosch 12114 Oxygen Sensor - Upstream

Bosch Oxygen Sensor for Toyota and Lexus

Bosch 12114 is a narrow-band, non-heated oxygen sensor built for specific upstream applications on select Toyota, Lexus, and Geo vehicles. It provides the air-fuel ratio signal the ECU uses to manage closed-loop fuel control and emissions performance.

Key Features

• Bosch Engineered Oxygen Sensor line with OE-focused design and calibration
• Specific fit replacement for upstream sensor locations
• Narrow-band, non-heated oxygen sensor type
• Round male connector with blade terminal and included wiring harness
• Flange mounting style with 18 mm thread diameter and 22 mm hex size
• Metal housing built for high-temperature and vibration exposure
• Part number 12114 for easy lookup and ordering

Product Details

Bosch 12114 is engineered for vehicles that use a switching-type upstream O2 sensor to monitor exhaust oxygen content and support precise fuel delivery. Bosch’s oxygen sensor development includes early thimble-style designs and later planar narrowband technology, giving this product line a long OE development history focused on faster sensor response, stable lambda measurement, and reliable closed-loop operation. This Bosch Engineered Oxygen Sensor is a direct replacement choice for 1992-1993 Toyota Camry upstream applications, 1992-1993 Lexus ES300 upstream applications, and other listed Toyota and Geo models. The Bosch 12114 is also cross-referenced to 8946539405 for the same application.

What It Helps Address

• Check engine light related to upstream oxygen sensor performance
• Incorrect air-fuel mixture readings sent to the ECU
• Rough idle or drivability issues tied to fuel control feedback
• Failed emissions inspection caused by a worn O2 sensor
• Slow sensor response in closed-loop fuel management

Installation Notes

Verify the vehicle’s upstream sensor location, connector style, and flange mounting before installation. This part is listed as a specific-fit replacement with a 14.8 overall length, 11.1 wiring harness length, and included wiring harness. Confirm the application details for California-emissions and non-California-emissions vehicles where noted, including 1992-1993 Toyota Camry upstream, 1992-1993 Lexus ES300 upstream, and 1994-1995 Toyota Celica upstream listings.

Quality Assurance

Bosch backs this oxygen sensor line with more than five decades of OE development and aftermarket supply experience. The design uses advanced ceramic elements, controlled heater strategy where applicable to the product family, and high-temperature-resistant materials to support consistent sensor output under demanding thermal and vibration conditions.