NTK 25509 Oxygen Sensor - Upstream

Direct Fit Oxygen Sensor for Porsche

NTK 25509 is a direct fit oxygen sensor built for specific Porsche applications. It uses a heated, threaded design with a 3-wire configuration and OE-style fit, form, and function for accurate air/fuel ratio feedback.

Key Features

• Direct fit oxygen sensor for specific applications
• Heated sensor design for faster operating response
• Threaded mounting type with 18 mm thread diameter
• 36.75-inch wiring harness length
• 3-wire configuration for the specified application

Detailed Description

NTK 25509 is part of the Direct Fit Oxygen Sensor line from NTK, a brand within the NGK family known for oxygen sensor coverage and OE application technology. NTK manufactures oxygen sensors with ceramic expertise and extensive production testing to meet or exceed OE specifications. This sensor is engineered for upstream use on Porsche 924, Porsche 944, and Porsche 968 applications listed in the fitment data, including Bank 1 Sensor 1 configurations where specified. The part number 25509 is also referenced in cross-application listings, including Bosch 13011.

For buyers searching for a Porsche 944 upstream oxygen sensor, Porsche 968 Bank 1 Sensor 1 oxygen sensor, or Porsche 924 Federal Emissions direct fit oxygen sensor, this NTK unit matches the listed application details and mounting style. The 25509 oxygen sensor is intended to restore proper exhaust feedback for the engine management system when the original sensor is worn or no longer responding correctly.

What It Is Used For

• Replacing a worn upstream oxygen sensor
• Addressing inaccurate air/fuel ratio feedback
• Correcting sensor response issues that affect engine management
• Restoring proper emissions-system monitoring

Installation Notes and Tips

Verify the vehicle year, model, and upstream position against the fitment table before ordering. Confirm the threaded mounting style, 18 mm thread diameter, and 3-wire harness length match the original sensor. Use the listed application notes for Bank 1 Sensor 1 and Federal Emissions coverage where applicable.

Quality Assurance

NTK tests oxygen sensors during manufacturing to help ensure quality and reliability that meet or exceed OE specifications.