Bosch 15986 Oxygen Sensor - Downstream

Bosch Validated Oxygen Sensor for Toyota Highlander

Bosch Validated Oxygen Sensor 15986 is a specific-fit, narrow-band heated O2 sensor for downstream applications on select Toyota Highlander models. It provides ECU air-fuel-ratio feedback for stable combustion control and emissions management, with OE-based engineering from Bosch’s long-running oxygen sensor development.

Key Features

• Specific-fit oxygen sensor for downstream placement
• Narrow-band heated sensor design for closed-loop fuel control
• 4-wire configuration with rectangular female connector
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Wiring harness included for direct replacement use
• Metal housing built for high-temperature and vibration exposure
• Bosch Validated Oxygen Sensor line for OE-style replacement needs

Product Details

Bosch part number 15986 is a standard replacement oxygen sensor engineered for precise switching-type signal output to the engine control unit. It uses a heated narrow-band design to support faster light-off and quicker closed-loop operation, helping the ECU maintain the correct air-fuel ratio during normal driving conditions. This Bosch Validated Oxygen Sensor is listed for 2004-2007 Toyota Highlander, downstream, and 2014-2019 Toyota Highlander, downstream. If you are searching for a Toyota Highlander downstream oxygen sensor or Bosch 15986 for Toyota Highlander emissions repair, this part matches those applications directly.

This part cross-references Toyota OE numbers 894650E110 and 8946548120 for the same application.

What It Helps Address

• Check engine light related to downstream oxygen sensor faults
• Incorrect oxygen sensor signal affecting fuel trim control
• Emissions test failures tied to sensor performance
• Rough or unstable closed-loop fuel management
• Delayed sensor response from a worn heated O2 sensor

Installation Notes

Verify the connector shape, 4-wire layout, threaded mount, and downstream location before installation. The sensor uses an 18 mm thread size and 22 mm hex, so the correct oxygen sensor socket or wrench is recommended. Confirm the vehicle year and engine application against the listed fitment for 2004-2007 Toyota Highlander and 2014-2019 Toyota Highlander before replacement.

Quality Assurance

Bosch has decades of OE oxygen sensor development behind this design, including early thimble-style sensors and later planar narrow-band technology. Bosch 15986 is built with ceramic sensing elements, controlled heater operation, and high-temperature materials to maintain consistent signal output under demanding thermal and vibration conditions.