Bosch 13566 Oxygen Sensor - Downstream

Bosch Oxygen Sensor for Toyota Sienna

Bosch 13566 is a specific-fit, narrow-band heated oxygen sensor for downstream use on select Toyota Sienna models. It provides the ECU with air-fuel-ratio feedback needed for stable closed-loop fuel control and emissions monitoring.

Key Features

• Specific-fit Bosch Engineered Oxygen Sensor for direct application matching
• Narrow-band heated O2 sensor design for downstream exhaust monitoring
• 4-wire configuration with rectangular male connector and blade terminals
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Wiring harness included with 9.6 in harness length and 11.8 in sealing-surface-to-connector length
• Metal housing and high-temperature-resistant construction for demanding exhaust conditions

Product Details

Bosch 13566 is built as a standard replacement oxygen sensor for the downstream position on 2001-2003 Toyota Sienna models. Bosch Engineered Oxygen Sensor products draw on decades of OE development, including narrowband sensor designs that improve response time and closed-loop operation compared with earlier sensor generations. This part cross-references 8946509290 for the same application.

For Toyota Sienna owners searching for a downstream oxygen sensor, Bosch 13566 offers the correct threaded fitment, heated sensor operation, and OE-style electrical connection layout. It is a practical choice when replacing a worn sensor that is affecting fuel trim control or emissions system performance.

What It Helps Address

• Check engine light related to downstream oxygen sensor performance
• Unstable air-fuel ratio feedback to the ECU
• Reduced closed-loop fuel control accuracy
• Emissions test failures tied to sensor response issues
• Rougher combustion control caused by an aging O2 sensor

Installation Notes

Verify the downstream location, connector style, thread size, and harness routing before installation. Use the correct oxygen sensor socket for the 22 mm hex and confirm the exhaust bung threads are clean and undamaged. Route the harness away from hot exhaust components and secure it to prevent abrasion or heat damage.

Quality Assurance

Bosch backs this oxygen sensor with more than five decades of OE sensor development and aftermarket supply experience. Bosch 13566 is engineered to deliver consistent signal accuracy and durable operation under heat and vibration typical of exhaust-system service.