NTK 25507 Oxygen Sensor - Upstream

Direct-Fit Oxygen Sensor

NTK 25507 is a direct-fit heated oxygen sensor built for specific California emissions applications. It is threaded for installation and uses a 3-wire design with a 36.5-inch harness for the listed Porsche fitments.

Key Features

• Heated oxygen sensor for faster signal response after startup.
• Specific-fit design for direct replacement on listed applications.
• Threaded mounting with an 18 mm thread diameter.
• 36.5-inch wiring harness and 3-wire configuration.
• OE-equivalent design for the listed Porsche 924 and Porsche 944 applications.

Detailed Description

NTK 25507 is part of the Direct Fit Oxygen Sensor line, which focuses on application-specific replacement sensors rather than universal coverage. NTK uses ceramic sensor technology and OE-focused manufacturing controls to deliver fit, form, and function aligned with original equipment requirements. This part cross-references OSC 13001 for the same application.

Compatible With 1983-1985 Porsche 944, upstream; 1986-1988 Porsche 944, upstream; and 1987-1988 Porsche 924, upstream. These applications are listed with California emissions and OE-equivalent direct-fit notes, making this oxygen sensor relevant for Porsche 944 and Porsche 924 repair work where the original sensor has failed or is no longer performing correctly. The part number 25507 is used throughout the catalog for this specific fitment.

What It Is Used For

• Replacing a failed upstream oxygen sensor.
• Restoring air-fuel feedback for emissions control.
• Addressing check engine light conditions tied to sensor output.
• Correcting poor fuel control caused by an aging heated sensor.
• Maintaining proper operation on California emissions applications.

Installation Notes and Tips

Use the listed threaded mounting style and verify the 18 mm thread diameter before installation. Confirm the vehicle is one of the specified Porsche 944 or Porsche 924 applications and match the upstream position and California emissions notes exactly. The 36.5-inch harness and 3-wire layout should be checked against the original routing before final fitment.

Quality Assurance

NTK states that its oxygen sensors are extensively tested during manufacturing and built to meet or exceed OE specifications. As part of the NGK family and a major original equipment oxygen sensor supplier, NTK 25507 is produced with OE-focused fit and reliability in mind.