Bosch 17018 Oxygen Sensor - Upstream

Bosch Wideband O2 Sensor for Subaru Upstream Applications

Bosch 17018 is an Actual OE Oxygen Sensor built as a wideband air-fuel sensor for precise upstream monitoring. It delivers continuous lambda measurement for accurate fuel control, stable drivability, and lower emissions on Subaru Forester, Impreza, Legacy, and Outback applications from 2000-2002.

Key Features

• Wideband A/F oxygen sensor with continuous air-fuel ratio measurement
• Heated design for faster sensor activity and stable operation
• Specific-fit replacement with 5-wire harness and 6 terminals
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Rectangle male connector with included wiring harness
• Robust metal housing and ceramic sensor construction for thermal durability
• Overall length: 18.1 in; harness length: 14.8 in

Detailed Description

Bosch 17018 is part of the Bosch Actual OE Oxygen Sensor line, which brings OE-proven sensor technology to the aftermarket. Bosch pioneered the wideband A/F oxygen sensor design, and this unit uses that approach to provide the ECU with detailed air-fuel data across the full lambda range. For Subaru Forester, Subaru Impreza, Subaru Legacy, and Subaru Outback upstream locations, that means more accurate mixture control than a traditional switching sensor can provide.

This Bosch wideband O2 sensor is a direct-fit, standard replacement part with a threaded mount, male connector, and integrated harness. It is built for fast light-off and consistent heater control, helping the engine management system respond quickly during cold starts, load changes, and normal driving.

This part cross-references Subaru 22791AA00A for the same application.

What It Helps Address

• Check engine light related to upstream oxygen sensor performance
• Incorrect air-fuel ratio readings sent to the ECU
• Rough idle or inconsistent throttle response caused by sensor drift
• Reduced fuel economy from inaccurate mixture control
• Elevated emissions from poor upstream sensor feedback

Installation Notes and Tips

• Fits 2000-2002 Subaru Forester, upstream.
• Fits 2000-2002 Subaru Impreza, upstream.
• Fits 2000-2002 Subaru Legacy, upstream.
• Fits 2000-2002 Subaru Outback, upstream.
• Confirm connector shape, wire count, and thread size before installation.
• Use proper oxygen sensor service tools to avoid damaging the threaded bung or sensor body.
• Inspect the harness routing and connector lock during installation to ensure a secure electrical connection.

Quality Assurance

Bosch backs this sensor with more than five decades of OE development in emission control and engine management components. The Actual OE Oxygen Sensor line is built to OE-level specifications for accurate signal output, reliable heater performance, and long-term durability in demanding thermal conditions.