Bosch 13720 Oxygen Sensor - Downstream or Downstream Left

Bosch 13720 Oxygen Sensor Overview

Bosch 13720 is a specific-fit, narrow-band heated oxygen sensor for downstream applications on select Toyota, Lexus, and Scion vehicles. It provides air-fuel-ratio feedback to the ECU to support stable combustion control and lower emissions across changing operating conditions.

As part of the Bosch Engineered Oxygen Sensor line, this sensor reflects Bosch’s OE development background and use of ceramic sensing elements, controlled heater operation, and high-temperature-resistant materials for consistent signal output in demanding exhaust environments.

Key Features

• Specific-fit Bosch oxygen sensor for direct replacement applications
• Narrow-band heated O2 sensor design for closed-loop fuel control
• 4-wire harness with square connector and male terminals
• Threaded mounting with 18 mm thread size and 22 mm hex size
• Wiring harness included; harness length measures 8.5 in
• Metal housing with steel finish for exhaust-side durability
• Overall length: 11.8 in; sealing surface to connector end: 10.6 in

Detailed Description

Bosch 13720 is built for downstream oxygen sensor service where accurate exhaust feedback matters for fuel trim control and emissions monitoring. This Bosch Engineered Oxygen Sensor uses a narrow-band heated design to help the ECU transition into closed-loop operation efficiently, while the threaded, specific-fit configuration supports direct replacement on the listed Toyota Camry, Toyota Highlander, Toyota Sienna, Toyota Venza, Lexus RX350, Lexus RX400h, Lexus RX450h, Lexus LS460, Lexus HS250h, Scion tC, Scion xB, and Scion iQ applications. The part number 13720 is commonly searched for downstream oxygen sensor replacement on these platforms.

This part cross-references Toyota/Lexus OE numbers such as 894650E020 and 894650E040 for the same application.

What It Helps Address

• Check engine light related to downstream oxygen sensor performance
• Slow or inaccurate air-fuel-ratio feedback to the ECU
• Emissions test failures tied to sensor response issues
• Rough combustion control caused by aging O2 sensor output
• Delayed closed-loop operation after warm-up

Installation Notes and Tips

Verify the vehicle’s exact year, engine, and downstream position before ordering, especially on 2014 Lexus RX350 and Toyota Venza applications with build-date notes. This sensor uses a threaded mount with a 18 mm thread diameter and a 22 mm hex, so the correct oxygen sensor socket or wrench is recommended. Confirm the connector shape, wire count, and harness routing against the original sensor before installation. Bosch 13720 is listed for downstream left and downstream positions only, depending on the vehicle application.

Quality Assurance

Bosch has more than five decades of OE oxygen sensor development behind this product line. The Bosch Engineered Oxygen Sensor range is built to OE-proven standards using durable materials and controlled heater technology for consistent operation in harsh exhaust conditions.