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NTK 25643 Oxygen Sensor - Downstream Left or Downstream Right
| Brand | NTK 25643 |
|---|---|
| Position | Downstream Right and Downstream Left |
| Wiring Harness Length | 33.7500 |
| 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 · 18 vehicles |
Direct fit design. Built for specific applications with OE-style fit, form, and function.
Heated sensor. Helps the sensor reach operating temperature faster for responsive exhaust monitoring.
OE-tested quality. Extensively tested during manufacturing to meet or exceed OE specifications.
Cross-references BBB Industries 13692, BBB Industries 13823 and BBB Industries 13824 for the same application. See all 14.
Will it fit your vehicle?
Free return shipping if it doesn't fit.
Direct Fit Oxygen Sensor for Audi
NTK Oxygen Sensor 25643 is a specific-fit, heated oxygen sensor built for downstream applications on select Audi models. It uses a threaded mounting design and a 4-wire configuration to match the original equipment style connection and signal requirements.
Key Features
- Specific-fit oxygen sensor for direct application matching
- Heated sensor design for faster operating response
- 4-wire configuration with threaded mounting
- 33.75-inch wiring harness length
- 18 mm thread diameter
Detailed Description
NTK 25643 is part of the Direct Fit Oxygen Sensor line, engineered to provide OE-style fit, form, and function for import and domestic applications. As an oxygen sensor for Audi A8, Audi A8 Quattro, and Audi A6 Quattro applications, it is built to meet the dimensional and electrical requirements of the original sensor location. The heated design and specific-fit construction support accurate exhaust monitoring in downstream positions, while the threaded mount and harness length help match the factory-style installation layout. This part cross-references DENSO Auto Parts 234-4662 for the same application.
What It Is Used For
- Replacing a worn or slow-responding downstream oxygen sensor
- Restoring proper exhaust gas monitoring signal output
- Addressing sensor fault codes related to oxygen sensor performance
- Correcting drivability issues tied to inaccurate air-fuel feedback
Installation Notes and Tips
Verify the downstream left or downstream right position and confirm the serial number note for 1998 Audi A6 Quattro applications before ordering. Match the 4-wire connector, 18 mm thread diameter, and harness length to the original sensor. Use the vehicle’s service information for proper removal and installation procedures.
Quality Assurance
NTK is a major original equipment oxygen sensor supplier, and this sensor is extensively tested during manufacturing to meet or exceed OE specifications.
| Year | Make | Model | Drive Type | Liters | Cylinders | Position | Notes |
|---|---|---|---|---|---|---|---|
| 1999 | Audi | A8 | — | 3.7L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 1999 | Audi | A8 | — | 3.7L | V8 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 1999 | Audi | A8 Quattro | — | 4.2L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 1999 | Audi | A8 Quattro | — | 4.2L | V8 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 1998 | Audi | A6 Quattro | AWD | 2.8L | V6 | Downstream Right | To Serial # 4A-W-005 000; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 1998 | Audi | A6 Quattro | AWD | 2.8L | V6 | Downstream Left | To Serial # 4A-W-005 000; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 1998 | Audi | A8 | — | 3.7L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 1998 | Audi | A8 | — | 3.7L | V8 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 1998 | Audi | A8 Quattro | — | 4.2L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 1998 | Audi | A8 Quattro | — | 4.2L | V8 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 1997 | Audi | A6 Quattro | AWD | 2.8L | V6 | Downstream Right | Equivalent OE design oxygen sensor; Direct Fit Oxygen Sensor |
| 1997 | Audi | A6 Quattro | AWD | 2.8L | V6 | Downstream Left | Equivalent OE design oxygen sensor; Direct Fit Oxygen Sensor |
| 1997 | Audi | A8 | — | 3.7L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 1997 | Audi | A8 | — | 3.7L | V8 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 1997 | Audi | A8 Quattro | — | 4.2L | V8 | Downstream Right | Downstream oxygen sensor with original equipment equivalent design; Direct Fit Oxygen Sensor |
| 1997 | Audi | A8 Quattro | — | 4.2L | V8 | Downstream Left | Oxygen Sensor B2S2 placement designed to OE specifications.; Direct Fit Oxygen Sensor |
| 1996 | Audi | A6 Quattro | AWD | 2.8L | V6 | Downstream Right | Equivalent OE design oxygen sensor; Direct Fit Oxygen Sensor |
| 1996 | Audi | A6 Quattro | AWD | 2.8L | V6 | Downstream Left | Equivalent OE design oxygen sensor; Direct Fit Oxygen Sensor |
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