NTK 25150 Oxygen Sensor - Downstream

Direct Fit Oxygen Sensor for Hyundai and Kia

The NTK 25150 is a direct fit heated oxygen sensor built for specific downstream applications on select Hyundai and Kia vehicles. It is engineered for OE-style fit, form, and function, with a threaded mounting design and a 4-wire configuration for straightforward replacement.

Compatible with 1999-2005 Hyundai Sonata, 2001-2006 Hyundai Santa Fe, 2001-2005 Kia Magentis, and 2001-2005 Kia Optima in downstream positions, this NTK oxygen sensor supports accurate exhaust feedback for vehicles that require a specific-fit replacement. The NTK 25150 is a practical choice when servicing a Hyundai Sonata downstream oxygen sensor or a Kia Optima downstream oxygen sensor.

Key Features

• Direct fit oxygen sensor for specific downstream applications
• Heated sensor design for faster operating response
• 4-wire configuration
• Threaded mounting type with 18 mm thread diameter
• Wiring harness length: 22.25 in.
• OE-style replacement for select Hyundai and Kia models

NTK Direct Fit Line

NTK’s Direct Fit Oxygen Sensor line focuses on application-specific replacements that match the original sensor layout and connector style. As part of the NGK family of products, NTK applies ceramic manufacturing expertise and OE application coverage to deliver sensors that align with factory requirements for import and domestic vehicles.

Detailed Description

The NTK 25150 oxygen sensor is designed for downstream use on select Hyundai and Kia vehicles, including the 1999-2005 Hyundai Sonata, 2001-2006 Hyundai Santa Fe, 2001-2005 Kia Magentis, and 2001-2005 Kia Optima. It uses a heated sensing element and a specific-fit, threaded design to match the original installation point and wiring layout. For buyers searching for a Hyundai Santa Fe downstream oxygen sensor or a Kia Magentis B1S2 oxygen sensor, this part number provides a direct replacement option built to OE specifications.

NTK manufactures oxygen sensors with extensive production testing to support quality and reliability. The 25150 is part of NTK’s OE-focused sensor coverage and is intended for vehicles that require a downstream sensor replacement with the correct harness length, wire count, and mounting style.

This part cross-references DENSO Auto Parts 234-4434 and Delphi ES20211 for the same application.

What It Helps Address

• Check engine light related to downstream oxygen sensor performance
• Incorrect exhaust feedback from a worn sensor
• Slow sensor response after extended service life
• Fault codes tied to B1S2 oxygen sensor operation
• Replacement needs after sensor contamination or heat-related wear

Installation Notes and Tips

Verify the vehicle year, make, model, and downstream position before ordering. This sensor uses a threaded mounting type and a 4-wire harness, so confirm connector routing and harness length against the original part. On 1999-2005 Hyundai Sonata applications, notes indicate use with a close-coupled catalyst in the manifold.

Quality Assurance

NTK tests oxygen sensors during manufacturing to support consistent quality and reliability. The brand’s OE-focused approach and ceramic manufacturing expertise are used to help ensure this replacement meets or exceeds original equipment specifications for the listed applications.