NTK 25641 Oxygen Sensor

Direct-Fit Oxygen Sensor

NTK 25641 is a direct-fit heated oxygen sensor built for specific Audi applications. It uses a threaded mounting design and a 4-wire configuration to match OE-style service requirements for accurate exhaust feedback.

Key Features

• Heated oxygen sensor for faster operating response
• Specific-fit design for direct application matching
• Threaded mounting type for secure installation
• 4-wire configuration with a 34.25-inch harness length
• NTK 25641 is engineered to meet or exceed OE specifications

Detailed Description

NTK 25641 is part of the Direct Fit Oxygen Sensor line, developed for import and domestic coverage with application-specific fitment. As an oxygen sensor for Audi RS6, Audi A8 Quattro, and Audi S8 applications, it supports precise exhaust monitoring in upstream and downstream positions listed in the fitment data. NTK 25641 combines a heated sensing element, threaded installation, and OE-style form to support consistent signal output and proper system operation. This part cross-references Bosch 16073 and DENSO Auto Parts 234-4812 for the same application.

What It Is Used For

• Replacing a worn or slow-responding oxygen sensor
• Restoring accurate air-fuel ratio feedback
• Addressing sensor fault codes related to exhaust monitoring
• Correcting drivability issues tied to improper sensor output
• Maintaining OE-style emissions system performance

Installation Notes and Tips

Verify the exact position and notes in the fitment table before installation. The sensor uses a threaded mount and a 4-wire harness, so connector routing and thread engagement should match the original layout. Confirm the application against the vehicle’s year, model, and sensor location before replacement.

Quality Assurance

NTK is part of the NGK family of products and is a major original equipment oxygen sensor supplier. Each sensor is extensively tested during manufacturing to help ensure quality and reliability that meet or exceed OE specifications.