Bosch 13257 Oxygen Sensor - Downstream Left or Downstream Right

Bosch Actual OE Oxygen Sensor 13257

Bosch 13257 is a narrow-band heated oxygen sensor built for precise air-fuel-ratio feedback to the ECU. It supports stable combustion control and emissions management for specific Nissan and INFINITI applications, including Pathfinder and QX4 downstream positions.

Key Features

• Actual OE Oxygen Sensor from Bosch’s OE-focused product line
• Narrow-band heated design for faster closed-loop operation
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• 4-wire configuration with square male connector and blade terminals
• Specific fit replacement with wiring harness included
• Metal housing and high-temperature-resistant construction for demanding exhaust conditions

Product Details

Bosch 13257 uses advanced ceramic sensing elements and controlled heater operation to deliver consistent signal output under changing exhaust temperatures. As part of Bosch’s Actual OE Oxygen Sensor line, it reflects the company’s long OE development history and narrow-band sensor expertise. This part number is used in downstream left and downstream right locations on select 1996-2000 Nissan Pathfinder models and 1997-2000 INFINITI QX4 applications, with an alternate fit note for some 2000 Nissan Pathfinder vehicles built to 12/1999. Bosch 13257 is a direct-fit replacement for drivers searching for a Bosch oxygen sensor for Nissan Pathfinder downstream right, a Bosch oxygen sensor for Nissan Pathfinder downstream left, or an INFINITI QX4 downstream oxygen sensor replacement.

This part cross-references Bosch OE-style application references for the same vehicle fitment.

Common Issues This Sensor Can Address

• Fault codes related to oxygen sensor response or heater circuit performance
• Unstable air-fuel mixture readings at the ECU
• Rough idle or drivability concerns tied to inaccurate exhaust feedback
• Failed emissions inspection caused by a worn downstream sensor
• Delayed closed-loop operation after startup

Installation Notes

Confirm the downstream left or downstream right position before ordering. Verify the 18 mm thread size, 4-wire connector layout, and square connector shape against the original sensor. Inspect the exhaust bung threads and wiring routing before installation, and transfer the sensor into a clean threaded mounting point for proper sealing and signal accuracy.

Quality Assurance

Bosch backs this oxygen sensor with OE development experience and materials selected for heat and vibration resistance. The design follows Bosch’s Actual OE approach for consistent replacement performance in emissions control service.