Bosch 18086 Oxygen Sensor - Downstream or Downstream Right

Bosch Validated Oxygen Sensor for Mercedes-Benz

Bosch Validated Oxygen Sensor 18086 is a specific-fit, narrow-band heated O2 sensor built for downstream use on select Mercedes-Benz applications. It provides the ECU with accurate air-fuel-ratio feedback to support stable combustion control and lower emissions.

Fits 2012-2015 Mercedes-Benz C250, downstream. Fits 2012-2015 Mercedes-Benz SLK250, downstream. This part cross-references Mercedes-Benz OE numbers 0065422218 and 68234701AB for the same application.

Key Features

• Specific-fit Bosch oxygen sensor for direct application matching
• Narrow-band heated sensor design for closed-loop fuel control
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• 4-wire harness with rectangular female connector and pin terminals
• Wiring harness included for cleaner replacement routing
• Metal housing and high-temperature materials for demanding exhaust conditions
• Overall length: 27.4 in; sealing surface to connector end: 26.2 in

Detailed Description

Bosch Part Number 18086 is part of the Bosch Validated Oxygen Sensor line, a product line focused on OE-style replacement coverage and application-specific fitment. Bosch has decades of oxygen sensor development behind this design, including narrow-band sensor technology that measures exhaust oxygen content and sends precise feedback to the engine control unit. On Mercedes-Benz C250 and Mercedes-Benz SLK250 models from 2012-2015, this downstream sensor helps maintain proper fuel trim control after the catalytic converter.

The sensor uses a heated narrow-band configuration with a threaded mount, female connector, and 4-wire layout. Its ceramic sensing element, optimized heater control, and heat-resistant construction are intended to maintain consistent signal output under thermal cycling and vibration. Bosch 18086 is a practical replacement choice when servicing a downstream Mercedes-Benz oxygen sensor circuit and restoring accurate emissions monitoring.

What This Sensor Helps Address

• Check engine light related to downstream oxygen sensor performance
• Incorrect air-fuel ratio feedback to the ECU
• Rough idle or unstable fuel control caused by aging sensor response
• Emissions test failures tied to sensor signal degradation
• Slow closed-loop operation after exhaust system service

Installation Notes and Tips

Verify the downstream location and connector style before installation on your Mercedes-Benz C250 or SLK250. Match the 18 mm thread size, 22 mm hex, and 4-wire rectangular female connector to the original sensor. Inspect the harness routing and exhaust-side connector condition during replacement, and confirm the sensor seats fully at the threaded mounting point.

Quality Assurance

Bosch builds this oxygen sensor using OE development experience and validated application coverage for consistent replacement performance. Bosch Part Number 18086 is engineered for the specified Mercedes-Benz fitments and is backed by Bosch’s long-standing oxygen sensor expertise.