NTK 25155 Oxygen Sensor - Downstream Left, Downstream Right or Upstream

Direct Fit Oxygen Sensor for Hyundai and Kia

NTK Direct Fit Oxygen Sensor 25155 is a heated, specific-fit replacement built for select Hyundai and Kia applications. It is engineered for direct replacement of the original sensor location, with OE-style fit, form, and function for accurate exhaust feedback.

Key Features

• Heated oxygen sensor for faster operating readiness
• Specific-fit design for direct replacement applications
• 4-wire configuration with 17.75 in. wiring harness length
• Threaded mounting with 18 mm thread diameter
• Built by NTK, a major OE oxygen sensor manufacturer

Product Details

NTK part number 25155 is part of the Direct Fit Oxygen Sensor line, which focuses on application-specific replacement sensors for import and domestic vehicles. NTK uses ceramic-based manufacturing control and extensive production testing to support consistent sensor performance and OE-level fitment. This oxygen sensor is listed for upstream and downstream positions on select Hyundai Santa Fe, Sonata, XG300, and Kia Magentis and Optima applications, including 2001-2006 Hyundai Santa Fe upstream and 1999-2005 Hyundai Sonata upstream. This part cross-references Bosch 13753 for the same application.

Vehicle Fitment

• Fits 2001-2006 Hyundai Santa Fe, Upstream — Bank 1 Sensor 1 Oxygen Sensor; Direct Fit Oxygen Sensor
• Fits 1999-2005 Hyundai Sonata, Upstream — B1S1; w/Close-Coupled Catalyst (In Manifold); OE MFR: NTK; Direct Fit Oxygen Sensor
• Fits 2001-2005 Kia Magentis, Upstream — Bank 1 Sensor 1 Oxygen Sensor; Direct Fit Oxygen Sensor
• Fits 2001-2005 Kia Optima, Upstream — Bank 1 Sensor 1 Oxygen Sensor; Direct Fit Oxygen Sensor
• Fits 2001 Hyundai XG300, Downstream Right — B1S2 oxygen sensor meets OEM standards.; Direct Fit Oxygen Sensor
• Fits 2001 Hyundai XG300, Downstream Left — Replacement oxygen sensor for B2S2 location.; Direct Fit Oxygen Sensor

Common Issues This Sensor Can Address

• Check engine light related to oxygen sensor circuit faults
• Incorrect air-fuel ratio feedback from a worn upstream sensor
• Slow sensor response that affects fuel control and emissions monitoring
• Failed emissions inspection caused by a malfunctioning O2 sensor
• Driveability concerns tied to inaccurate exhaust oxygen readings

Installation Notes and Tips

Confirm the sensor position before ordering, since this NTK 25155 application covers upstream and downstream locations depending on vehicle and engine configuration. Match the threaded mounting style, 4-wire connector layout, and harness length to the original sensor before installation. For best results, inspect the exhaust threads and connector condition during replacement.

Quality Assurance

NTK manufactures oxygen sensors with OE application coverage and production testing to help ensure reliable operation and consistent fit. As part of the NGK family of products, NTK supports import and domestic sensor applications with OE-focused engineering and manufacturing control.