Bosch 15802 Oxygen Sensor - Downstream

Bosch Validated Oxygen Sensor for Ford Focus

Bosch 15802 is a narrow-band heated oxygen sensor built for downstream use on select Ford Focus models. It provides the ECU with air-fuel-ratio feedback after the secondary converter, helping maintain stable combustion control and emissions performance.

The Bosch Validated Oxygen Sensor line draws on Bosch OE development in oxygen sensing, including narrowband designs that respond quickly and support accurate closed-loop operation. This Bosch 15802 replacement uses a threaded, 4-wire configuration with a rectangular male connector and included wiring harness for a direct-fit service part.

Key Features

• Fits select 2004-2007 Ford Focus downstream locations
• Downstream sensor placement after the secondary converter or catalyst, depending on application
• Narrow-band heated oxygen sensor for standard replacement service
• 4-wire design with blade terminals and rectangular male connector
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Metal housing and high-temperature-resistant construction for demanding exhaust conditions
• Wiring harness included for the specified application
• Bosch part number 15802

Detailed Description

Bosch 15802 is a specific-fit oxygen sensor for Ford Focus models listed below, positioned downstream to monitor exhaust conditions after the catalyst or secondary converter. It is a narrow-band heated sensor that sends precise feedback to the engine control unit, supporting closed-loop fuel control and emissions monitoring. The Bosch Validated Oxygen Sensor line reflects Bosch’s long OE history in oxygen sensing, with ceramic sensing elements, controlled heater operation, and durable materials selected for thermal and vibration exposure. This part number 15802 is a practical replacement choice when servicing a downstream Ford Focus oxygen sensor circuit.

Fits 2005-2007 Ford Focus, downstream. Fits 2006 Ford Focus, downstream. Fits 2004 Ford Focus, downstream. Fits 2005 Ford Focus, downstream. Fits 2006 Ford Focus, downstream. Bosch 15802 is also listed for 2004-2007 Ford Focus downstream applications with notes for secondary converter placement, heat shield routing, and PZEV/production-date exceptions where specified.

Common Issues This Part Can Address

• Check engine light related to downstream oxygen sensor performance
• Incorrect catalyst efficiency readings from the exhaust monitoring system
• Delayed or unstable closed-loop fuel control after sensor aging
• Fault codes tied to heater circuit or sensor response problems
• Emissions test failures caused by a worn oxygen sensor

Installation Notes and Tips

Verify the connector shape, wire count, thread size, and downstream location before installation. On the Ford Focus, some listed applications place the sensor after the secondary converter or below the heat shield after the catalyst, so confirm the exact routing and production-date notes for your vehicle. Use the correct 18 mm oxygen sensor socket and inspect the harness path to avoid heat damage.

Quality Assurance

Bosch has more than five decades of OE oxygen sensor development, and the Bosch Validated Oxygen Sensor line is built to the same OE-proven standards used by vehicle manufacturers. This part number 15802 is engineered for consistent signal output and durable service in exhaust-system conditions.