Bosch 15418 Oxygen Sensor - Downstream Left, Downstream Right or Upstream

Bosch Oxygen Sensor for Toyota Applications

Bosch Part Number 15418 is a narrow-band heated oxygen sensor built for specific Toyota fitments, including 1999-2000 Toyota 4Runner and 2000-2004 Toyota Tundra applications. It provides direct air-fuel-ratio feedback to the ECU for stable closed-loop fuel control and emissions monitoring.

The Bosch Engineered Oxygen Sensor line draws on Bosch OE development in oxygen sensing, including narrowband designs that improve response time and help the engine management system reach closed-loop operation quickly. Bosch 15418 is a standard replacement sensor with a 4-wire harness, rectangular male connector, and flange mounting style.

Key Features

• Specific-fit oxygen sensor for select Toyota 4Runner and Toyota Tundra applications
• Narrow-band heated design for accurate exhaust oxygen feedback
• 4-wire configuration with included wiring harness
• Rectangular male connector with blade terminals
• Metal housing with high-temperature-resistant construction
• 18 mm thread size and 22 mm hex for service replacement
• Bosch Part Number 15418 for easy identification

Detailed Description

Bosch 15418 is engineered as a switching-type oxygen sensor that reports exhaust oxygen content to the ECU so the fuel system can maintain the proper air-fuel ratio. This matters on vehicles such as the Toyota 4Runner and Toyota Tundra, where precise sensor feedback supports stable combustion control and emissions performance across changing operating conditions. The heated narrow-band design helps the sensor reach operating temperature faster and maintain consistent signal output under thermal and vibration stress.

Bosch Engineered Oxygen Sensor products are backed by decades of OE development, and this part reflects that approach with a durable ceramic sensing element, optimized heater control, and materials selected for high-temperature service. If you are replacing a worn sensor on a 1999-2000 Toyota 4Runner or a 2000-2004 Toyota Tundra, Bosch 15418 provides a direct-fit service solution. This part cross-references Denso 8946509130 and 8946509380 for the same application.

What It Helps Address

• Check engine lights related to oxygen sensor performance
• Rough idle or unstable fuel trim caused by inaccurate O2 feedback
• Delayed closed-loop operation after startup
• Reduced emissions performance from a slow or aging sensor
• Fuel control issues tied to degraded narrow-band signal output

Installation Notes and Tips

Verify the sensor position before ordering: this Bosch 15418 application list includes upstream and downstream locations depending on year and model. Confirm connector shape, wire count, thread size, and harness length against the original sensor before installation. For best results, inspect the exhaust bung threads and wiring routing, and ensure the sensor is installed in the correct bank and position for the vehicle.

Compatible With 1999 Toyota 4Runner, upstream from 10/1998 without California Emission System; 1999-2000 Toyota 4Runner, upstream without California Emission System; 2000 Toyota Tundra, upstream without California Emission System; 2003-2004 Toyota Tundra, downstream left; 2003-2004 Toyota Tundra, downstream right.

Quality Assurance

Bosch has more than five decades of oxygen sensor development and supplies OE-proven sensor technology to the aftermarket. Bosch 15418 is built to the same engineering standards associated with Bosch Engineered Oxygen Sensor products, with a focus on accurate signal output, heater performance, and long-term durability in demanding exhaust environments.