NTK 25550 Oxygen Sensor

Direct-Fit Oxygen Sensor for Audi and Volkswagen

NTK 25550 is a direct-fit heated oxygen sensor built for specific import applications. It uses a threaded mounting design and a 4-wire configuration with a 29.25-inch harness for OE-style replacement on supported Audi and Volkswagen models.

As part of NTK's Direct Fit Oxygen Sensor line, this sensor is engineered for streamlined coverage and application-specific fitment. NTK 25550 is built to match the original sensor layout, helping maintain accurate exhaust feedback on vehicles such as the Audi A4, Audi A6, and Volkswagen Passat.

Key Features

• Direct-fit oxygen sensor for specific applications
• Heated sensor design for faster operating response
• 4-wire configuration with threaded mounting type
• 29.25-inch wiring harness length
• 18 mm thread diameter
• NTK 25550 part number for catalog matching

Detailed Description

NTK 25550 is an OE-style oxygen sensor from NTK's Direct Fit Oxygen Sensor product line, designed for exact-application replacement rather than universal use. The sensor is threaded for installation in the exhaust stream and uses a heated design to support stable signal output once the system reaches operating temperature. With specific fitment across Audi A4, Audi A4 Quattro, Audi A6, Audi A6 Quattro, Audi A8, Audi A8 Quattro, Volkswagen EuroVan, Golf, Jetta, and Passat applications, it serves as a direct replacement option for upstream and downstream positions listed in the fitment data. The NTK 25550 part number is also useful when cross-checking catalog listings for the same application.

This part cross-references Bosch (e.g., 13736, 13842) for the same application.

What It Helps Address

• Faulty oxygen sensor readings that can trigger engine management concerns
• Slow sensor response from a worn heated oxygen sensor
• Incorrect air-fuel feedback in supported upstream or downstream locations
• Replacement needs for a threaded, direct-fit sensor with the correct harness length
• Catalog matching for the NTK 25550 application

Installation Notes and Quality

Verify the year, make, model, and sensor position against the fitment table before installation. Confirm the thread diameter, wire count, and harness length match the original sensor configuration. This sensor is intended for specific applications only, so use the listed fitment notes for Bank 1 Sensor 1, upstream, or downstream coverage where shown.

NTK is part of the NGK family of products and is recognized as a major original equipment oxygen sensor supplier. Each sensor is extensively tested during manufacturing to meet or exceed OE specifications for fit, form, and function.