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NTK 25725 Oxygen Sensor - Downstream, Downstream Left or Downstream Right
| Brand | NTK 25725 |
|---|---|
| Position | Downstream Left, Downstream, and Downstream Right |
| Wiring Harness Length | 26.5000 |
| Sensor Type | Heated |
| Universal Or Specific Fit | Specific |
| Wire Quantity | 4 |
| Thread Diameter | 18.000 |
| Mounting Type | Threaded |
| Product line | Direct Fit Oxygen Sensor |
| Fits | Audi, Bentley, and Volkswagen · 48 vehicles |
Direct fit design. Specific replacement for supported oxygen sensor applications.
Heated sensor. Helps the sensor reach operating temperature quickly.
OE-equivalent construction. Built to match original equipment fit, form, and function.
Cross-references Bosch 16136, Bosch 16227 and Bosch 16862 for the same application. See all 19.
Will it fit your vehicle?
Free return shipping if it doesn't fit.
Direct Fit Oxygen Sensor for Import Applications
NTK oxygen sensor 25725 is a direct fit, threaded heated sensor built for specific applications with OE-equivalent design. It uses a 4-wire layout and a 26.5-inch harness for a precise replacement on supported Audi and Volkswagen models, including downstream locations.
Key Features
- Heated oxygen sensor for faster operating response
- Specific-fit design for direct replacement on listed applications
- Threaded mounting type with 18 mm thread diameter
- 4-wire configuration with 26.5-inch harness length
- OE-equivalent design for supported Audi and Volkswagen fitments
Detailed Description
NTK 25725 is part of the Direct Fit Oxygen Sensor line, engineered for exact application coverage rather than universal use. This sensor is listed for downstream positions on select Audi A8 Quattro, S6, S7, S8, RS7, RS4, A6 Quattro, and A3 Quattro models, plus Volkswagen Eos, R32, and Passat applications. It is also listed for a 2015 Bentley Continental downstream application. NTK uses OE application technology and manufacturing controls to deliver fit, form, and function aligned with original equipment requirements. This part cross-references Bosch (e.g., 16136, 16227) for the same application.
What It Is Used For
- Replacing a failed downstream oxygen sensor
- Addressing check engine light concerns tied to oxygen sensor performance
- Restoring proper exhaust gas feedback to the engine control system
- Correcting drivability issues caused by inaccurate sensor readings
- Replacing a sensor with the wrong connector or harness configuration
Installation Notes and Tips
Verify the vehicle year, make, model, and downstream position before installation. Confirm the sensor uses the correct B2S2 or B3S2 application note where listed, and match the threaded mounting style, wire count, and harness length to the original part. Use the fitment table to confirm exact coverage for Audi, Volkswagen, and Bentley applications.
Quality Assurance
NTK states that these oxygen sensors are extensively tested during manufacturing to meet or exceed OE specifications. The brand is part of the NGK family and is recognized as a major original equipment oxygen sensor supplier.
| Year | Make | Model | Liters | Cylinders | Position | Notes |
|---|---|---|---|---|---|---|
| 2018 | Audi | A8 Quattro | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2018 | Audi | S6 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2018 | Audi | S8 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2017 | Audi | A8 Quattro | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2017 | Audi | RS7 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2017 | Audi | S6 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2017 | Audi | S7 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2017 | Audi | S8 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2016 | Audi | A8 Quattro | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2016 | Audi | RS7 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2016 | Audi | S6 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2016 | Audi | S7 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2016 | Audi | S8 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2015 | Audi | A8 Quattro | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2015 | Audi | RS7 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2015 | Audi | S6 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2015 | Audi | S7 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2015 | Audi | S8 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2015 | Bentley | Continental | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2014 | Audi | A8 Quattro | 6.3L | W12 | Downstream | Cyls. 7-9; B3S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2014 | Audi | A8 Quattro | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2014 | Audi | RS7 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2014 | Audi | S6 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2014 | Audi | S7 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2014 | Audi | S8 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2013 | Audi | A8 Quattro | 6.3L | W12 | Downstream | Cyls. 7-9; B3S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2013 | Audi | A8 Quattro | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2013 | Audi | S6 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2013 | Audi | S7 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2013 | Audi | S8 | 4.0L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2012 | Audi | A8 Quattro | 6.3L | W12 | Downstream | Cyls. 7-9; B3S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2011 | Audi | A6 Quattro | 4.2L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 2011 | Audi | A8 Quattro | 4.2L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2010 | Audi | A6 Quattro | 4.2L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 2009 | Audi | A3 Quattro | 3.2L | V6 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 2009 | Audi | A6 Quattro | 4.2L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 2008 | Audi | A3 Quattro | 3.2L | V6 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 2008 | Audi | A6 Quattro | 4.2L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 2008 | Audi | RS4 | 4.2L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2008 | Volkswagen | Eos | 3.2L | V6 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 2008 | Volkswagen | R32 | 3.2L | V6 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 2007 | Audi | A3 Quattro | 3.2L | V6 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 2007 | Audi | A6 Quattro | 4.2L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 2007 | Audi | RS4 | 4.2L | V8 | Downstream | Cyls. 5-8; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 2007 | Volkswagen | Eos | 3.2L | V6 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 2007 | Volkswagen | Passat | 3.6L | V6 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 2006 | Audi | A3 Quattro | 3.2L | V6 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 2006 | Volkswagen | Passat | 3.6L | V6 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
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