NTK 24521 Oxygen Sensor - Upstream, Upstream Left or Upstream Right

Direct Fit Oxygen Sensor for OE Applications

NTK Oxygen Sensor 24521 is a heated, specific-fit replacement built for direct installation on select Nissan, Infiniti, and Mercury applications. It is engineered for upstream air/fuel ratio monitoring where accurate exhaust feedback is critical to engine management.

As part of the NTK Direct Fit Oxygen Sensor line, this sensor focuses on OE-style fit, form, and function for import and domestic coverage. It is a threaded, 3-wire sensor with an 18 mm thread diameter and a 17.75 in. wiring harness length.

Key Features

• Heated oxygen sensor for faster operating temperature and stable signal output
• Specific-fit design for direct replacement on listed vehicles
• Threaded mounting type with 18 mm thread diameter
• 3-wire configuration with 17.75 in. wiring harness length
• Built by NTK, the Sensor Specialist, with OE-focused application coverage
• Part number 24521 for easy catalog matching

Product Details

NTK 24521 is part of the Direct Fit Oxygen Sensor product line, which is built around streamlined coverage and OE application technology. NTK uses ceramic manufacturing expertise and controlled production processes to support consistent sensor performance from raw material through finished product. The sensor is extensively tested during manufacturing to help meet or exceed OE specifications for fit and reliability.

This oxygen sensor is used in upstream positions on a wide range of vehicles, including Nissan Frontier, Nissan Xterra, Nissan Pathfinder, Nissan Quest, Nissan Sentra, Nissan 200SX, Nissan NX, Infiniti QX4, Infiniti G20, Infiniti I30, Infiniti Q45, Infiniti Q45, and Mercury Villager applications. Fits 1999-2003 Nissan Frontier, Upstream Right; Fits 2000-2003 Nissan Xterra, Upstream Right; Fits 1996-2000 Nissan Pathfinder, Upstream Right; Fits 2001-2002 Nissan Quest, Upstream; Fits 1997-1999 Nissan Sentra, Upstream.

This part cross-references Bosch 13091 and Denso Auto Parts 234-3087 for the same application.

Common Issues This Sensor Can Address

• Fault codes related to oxygen sensor response or heater circuit performance
• Rough idle caused by inaccurate exhaust oxygen feedback
• Reduced fuel control accuracy from a worn upstream sensor
• Emission test failures tied to aging sensor output
• Check engine light concerns on listed Nissan, Infiniti, and Mercury models

Installation Notes and Tips

• Verify the vehicle year, make, model, and sensor position before ordering.
• Confirm the application is upstream right, upstream left, or upstream as listed for your vehicle.
• Inspect the connector routing and harness length before installation.
• Use the threaded mounting point and proper oxygen sensor service tools to avoid thread damage.
• Clear diagnostic trouble codes after installation and confirm normal sensor operation.

Quality Assurance

NTK manufactures oxygen sensors with OE-focused testing and application coverage. The brand’s Direct Fit Oxygen Sensor line is developed to support accurate fitment and dependable performance on import and domestic vehicles.