Bosch 13271 Oxygen Sensor - Downstream

Bosch Actual OE Oxygen Sensor for Nissan 240SX

Bosch 13271 is a narrow-band heated oxygen sensor built for precise air-fuel-ratio feedback to the ECU. It is a specific-fit replacement for the downstream position on 1997-1998 Nissan 240SX models, helping maintain stable closed-loop fuel control and lower emissions.

The Bosch Actual OE Oxygen Sensor line draws on Bosch’s long OE development history, including early thimble-style sensor designs and later planar narrowband technology. This product uses a ceramic sensing element, controlled heater operation, and high-temperature-resistant materials for consistent signal output in demanding exhaust conditions.

Key Features

• Part number 13271
• Specific-fit downstream oxygen sensor
• Fits 1997-1998 Nissan 240SX, downstream
• Narrow-band heated oxygen sensor design
• 4-wire configuration with square male connector
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Steel finish with metal housing for exhaust-area durability
• Wiring harness length: 9.3 in

Detailed Description

Bosch 13271 is an OE-style oxygen sensor for vehicles that use a narrow-band heated sensor in the downstream exhaust position. For 1997-1998 Nissan 240SX applications, it provides the ECU with the exhaust oxygen feedback needed for accurate fuel trim control after combustion. The Bosch Actual OE Oxygen Sensor line is engineered around precise signal response, heater performance, and durability under heat and vibration.

This part cross-references Monroe Shocks & Struts (e.g., 226A081F12) for the same application. If you are searching for a downstream oxygen sensor for Nissan 240SX 1997-1998, Bosch 13271 is the direct OE-style replacement to verify against your original sensor connector, thread size, and wire count.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Incorrect air-fuel ratio feedback to the ECU
• Rough idle or unstable fuel control from a worn downstream sensor
• Failed emissions inspection caused by sensor response issues
• Slow closed-loop operation after exhaust heat cycling

Installation Notes and Tips

Confirm the downstream location, connector shape, wire count, and 18 mm thread size before installation. Use the existing exhaust bung and verify the sensor reaches the connector without strain; the sealing-surface-to-connector length is 11.8 in. Because this is a threaded oxygen sensor, proper removal and installation tools help reduce the risk of damaging the exhaust threads.

Quality Assurance

Bosch supplies this Actual OE Oxygen Sensor line with OE-proven engineering based on decades of oxygen sensor development and aftermarket support. The design focuses on accurate signal output, heater control, and long-term performance in high-temperature exhaust environments.