Bosch 13281 Oxygen Sensor - Upstream

Bosch Oxygen Sensor for Toyota Upstream Applications

Bosch Part Number 13281 is a specific-fit, narrow-band heated oxygen sensor for select Toyota applications, including 1988-1989 Toyota Pickup upstream and 1988-1989 Toyota 4Runner upstream. It uses a 4-wire design with a square male connector, blade terminals, and an included wiring harness for direct replacement service.

Key Features

• Specific-fit Bosch Engineered Oxygen Sensor, part number 13281
• Narrow-band heated O2 sensor for closed-loop fuel control
• 4-wire configuration with square male connector and blade terminals
• Flange mounting style with 18 mm thread diameter and 22 mm hex size
• Wiring harness included; harness length measures 29.2 in
• Metal housing with high-temperature-resistant construction
• Fits 1988-1989 Toyota Pickup upstream and 1988-1989 Toyota 4Runner upstream

Detailed Description

Bosch 13281 is part of the Bosch Engineered Oxygen Sensor line, built around Bosch’s long OE development history in oxygen sensing technology. This narrow-band heated sensor measures exhaust oxygen content and sends air-fuel-ratio data to the ECU so the engine can maintain stable combustion control and emissions performance under changing operating conditions. For Toyota 4Runner and Toyota Pickup upstream service, Bosch 13281 provides the correct specific-fit configuration for direct replacement use.

The sensor uses a heated ceramic element for faster light-off and quicker closed-loop operation, while the 4-wire layout supports efficient signal and heater control. Its flange mount, 18 mm thread size, and square connector help match the original application requirements. This part cross-references Bosch 13281 for the same application.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Rich or lean fuel mixture concerns
• Slow closed-loop fuel control response
• Inconsistent idle quality caused by inaccurate O2 feedback
• Emissions test failures tied to upstream sensor faults

Installation Notes and Tips

Verify the upstream sensor location before installation and confirm the connector shape, thread size, and harness routing match the original part. Use the correct 22 mm oxygen sensor socket and avoid contaminating the sensing tip during handling. Inspect the exhaust bung threads and wiring path before tightening the sensor into place.

Quality Assurance

Bosch supplies oxygen sensors with OE-proven engineering and durable materials designed for high heat and vibration exposure. Bosch 13281 is built to deliver accurate air-fuel feedback for the listed Toyota applications, including 1988-1989 Toyota Pickup upstream and 1988-1989 Toyota 4Runner upstream.