Bosch 12109 Oxygen Sensor - Downstream or Upstream

Bosch Oxygen Sensor for Toyota Applications

Bosch 12109 is a specific-fit narrow-band oxygen sensor built for Toyota vehicles that need accurate air-fuel ratio feedback at the ECU. It is a standard replacement sensor with a threaded mount, 18 mm thread size, and a 22 mm hex for service access.

Compatible with select Toyota Camry and Toyota Celica applications, this Bosch Engineered Oxygen Sensor uses a 2-wire layout, male blade terminals, and a rectangular connector with a 22.5 in wiring harness length. Bosch’s oxygen sensor line is based on decades of OE development, with sensor designs that focus on stable closed-loop control, fast response, and durable operation in high-heat, high-vibration environments.

Key Features

• Bosch part number 12109
• Specific-fit narrow-band oxygen sensor
• Non-heated design with 2-wire construction
• Threaded mounting with 18 mm thread diameter
• Male blade terminals and rectangular connector
• Wiring harness included for direct replacement use
• Steel finish with metal housing for underbody durability
• Fits upstream and downstream Toyota applications listed below

Fitment Details

• Fits 1996-1997 Toyota Celica, upstream.
• Fits 1996 Toyota Camry, downstream.
• Fits 1993 Toyota Camry, downstream.
• Fits 1994-1995 Toyota Camry, downstream, without California Emission System.
• Fits 1994-1995 Toyota Camry, downstream, with California Emission System.
• Fits 1992 Toyota Camry, downstream, with California Emission System.

What This Sensor Helps Address

• Incorrect oxygen sensor signal to the ECU
• Unstable air-fuel ratio control during closed-loop operation
• Check engine light concerns related to sensor performance
• Rough combustion caused by delayed or inaccurate sensor feedback
• Emissions-related drivability issues on Toyota Camry and Toyota Celica models

Installation Notes

Verify the sensor position before ordering, since Bosch 12109 is listed for both upstream and downstream locations depending on the vehicle. Confirm the connector style, thread size, and harness length against the original sensor before installation. This part cross-references Bosch-style OE applications (e.g., 8946520500, 8946533010) for the same application.

Quality Assurance

Bosch Engineered Oxygen Sensor products are backed by more than five decades of OE development and are built to meet the demands of modern emission control systems. Bosch 12109 reflects that OE-focused engineering approach for Toyota Camry and Toyota Celica service replacement needs.