Bosch 18003 Oxygen Sensor - Downstream Right

Bosch OE Oxygen Sensor for Nissan

Bosch 18003 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 the 2004 Nissan Frontier and 2004 Nissan Xterra, both in the downstream right position.

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. That engineering focus is reflected in faster light-off, accurate lambda measurement, and reliable closed-loop operation under heat and vibration.

Key Features

• Part number 18003 Bosch Actual OE Oxygen Sensor
• Specific fit for 2004 Nissan Frontier and 2004 Nissan Xterra
• Downstream right oxygen sensor application
• Narrow-band heated sensor design for closed-loop fuel control
• 4-wire configuration with square male connector
• Threaded mounting with 18 mm thread size and 22 mm hex
• Wiring harness included; harness length 30.7 in
• Metal housing with steel finish for underbody service conditions

Product Details

Bosch 18003 is a standard replacement oxygen sensor that measures exhaust oxygen content and sends that signal to the engine control unit. For 2004 Nissan Frontier and 2004 Nissan Xterra downstream right service, it provides the OE-style sensor response needed for accurate fuel trim control, emissions monitoring, and consistent drivability. The Bosch Actual OE Oxygen Sensor line is built with advanced ceramic elements, controlled heater operation, and high-temperature materials to maintain performance in demanding exhaust environments.

This part cross-references Nissan 226A0EK800 for the same application.

Common Issues This Sensor Can Address

• Check engine light related to oxygen sensor performance
• Incorrect air-fuel ratio feedback to the ECU
• Rough idle or unstable closed-loop fuel control
• Increased emissions from a slow or inaccurate downstream sensor
• Delayed sensor response after exhaust heat-up

Installation Notes

Install Bosch 18003 in the threaded downstream right location on the exhaust system. Verify connector shape, wire count, and harness length before installation, and confirm the sensor threads and hex size match the vehicle bung. Because this is a heated narrow-band sensor, proper connector routing and secure harness placement are important to avoid heat damage and vibration wear.

Quality Assurance

Bosch supplies OE-developed oxygen sensors to the aftermarket using the same engineering approach trusted by vehicle manufacturers. The Bosch 18003 is built for accurate signal output, durable heater performance, and consistent operation in high-temperature exhaust service.