NTK 25591 Oxygen Sensor - Downstream or Intermediate

Direct Fit Oxygen Sensor for Volvo Applications

NTK Direct Fit Oxygen Sensor 25591 is a heated, specific-fit replacement built for select Volvo models with OE-equivalent design. It is engineered for the intermediate center sensor on 2005-2010 Volvo S40 and V50, and for downstream sensor locations on select 1999-2001 Volvo S70, 1999-2001 Volvo V70, and 2001 Volvo S60 applications.

As part of the NTK Direct Fit Oxygen Sensor line, this sensor focuses on correct connector fit, proper harness length, and application-specific mounting for straightforward replacement service. NTK 25591 is built with OE-style form and function for Volvo S40 oxygen sensor replacement and Volvo V50 downstream oxygen sensor service.

Key Features

• Heated oxygen sensor for faster operating temperature response
• Specific-fit design for direct replacement on listed Volvo applications
• 4-wire configuration for the correct signal and heater circuit layout
• 32-inch wiring harness length for application-specific routing
• 18 mm threaded mounting type
• OE-equivalent design for select intermediate and downstream sensor positions

Detailed Product Overview

NTK is known for oxygen sensor manufacturing across import and domestic applications, and part number 25591 reflects that focus with a direct-fit design for select Volvo platforms. The sensor uses NTK’s ceramic manufacturing expertise and is extensively tested during production to help maintain quality and reliability aligned with OE specifications. For buyers searching for a Volvo S40 B1S2 oxygen sensor, Volvo V50 center sensor replacement, or a downstream oxygen sensor for Volvo S70, V70, or S60, this part provides a targeted application match.

This part cross-references Bosch 15035 and DENSO Auto Parts 234-4734 for the same application.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Incorrect air-fuel ratio feedback from a worn sensor
• Slow sensor response during closed-loop operation
• Fault codes tied to intermediate or downstream sensor circuits
• Emissions test failures caused by degraded sensor output

Installation Notes and Tips

Verify the sensor position before installation: this application covers intermediate center sensor and downstream locations depending on vehicle year and model. Confirm connector style, harness routing, and threaded mounting requirements against the original part before replacement. Use the listed fitment details for 2005-2010 Volvo S40 and V50, plus 1999-2001 Volvo S70 and V70 and 2001 Volvo S60, to match the correct sensor location.

Quality Assurance

NTK manufactures oxygen sensors with OE-focused engineering and production testing to support fit, form, and function on the listed Volvo applications. The brand’s role as a major original equipment oxygen sensor supplier supports consistent application coverage and manufacturing control.