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NTK 25512 Oxygen Sensor - Upstream
| Brand | NTK 25512 |
|---|---|
| Position | Upstream |
| Wiring Harness Length | 69.2500 |
| Sensor Type | Heated |
| Universal Or Specific Fit | Specific |
| Wire Quantity | 3 |
| Thread Diameter | 18.000 |
| Mounting Type | Threaded |
| Product line | Direct Fit Oxygen Sensor |
| Fits | BMW · 9 vehicles |
Direct fit design. Built for specific applications with OE-style fit, form, and function.
Heated sensor. 3-wire construction supports responsive exhaust feedback.
OE supplier pedigree. NTK draws on original equipment oxygen sensor manufacturing expertise.
Cross-references Bosch 13049, OSC 13059 and 75-1556 for the same application. See all 13.
Will it fit your vehicle?
Free return shipping if it doesn't fit.
Direct Fit Oxygen Sensor
NTK 25512 is a direct fit heated oxygen sensor for specific BMW applications. It is built with a threaded mounting design and a 3-wire configuration for accurate air/fuel ratio feedback in upstream locations.
Key Features
- Direct fit design for specific applications
- Heated oxygen sensor construction
- 3-wire configuration
- Threaded mounting type
- 69.25-inch wiring harness length
- 18 mm thread diameter
Detailed Description
NTK 25512 is part of the Direct Fit Oxygen Sensor line, engineered for specific import and domestic applications with OE-style fit, form, and function. NTK applies ceramic sensor manufacturing expertise and extensive production testing to deliver a replacement oxygen sensor that meets or exceeds OE specifications. This part number is used in upstream BMW 535i, 635CSi, L6, L7, M5, and M6 applications, including BMW 635CSi fitments for cylinders 1-3 and cylinders 4-6. The 25512 supports air/fuel ratio monitoring where precise sensor response is required.
This part cross-references Bosch 13049 and OSC 13059 for the same application.
What It Is Used For
- Replacing a failed upstream oxygen sensor
- Restoring air/fuel ratio signal accuracy
- Addressing check engine light concerns related to sensor performance
- Correcting drivability issues caused by inaccurate exhaust feedback
- Replacing a sensor with worn heater or signal response
Installation Notes and Tips
Verify the connector, harness length, thread diameter, and mounting style before installation. Confirm the vehicle’s bank and sensor location against the listed fitment, since this part is specific to upstream BMW applications. Use the fitment notes to match the correct cylinder group or sensor position for the application.
Quality Assurance
NTK is a major original equipment oxygen sensor supplier and tests these sensors during manufacturing to help ensure quality and reliability that meet or exceed OE specifications.
| Year | Make | Model | Liters | Cylinders | Position | Notes |
|---|---|---|---|---|---|---|
| 1988 | BMW | 635CSi | 3.5L | L6 | Upstream | Cylinders 1-3, Bank 1 Sensor 1, OE Equivalent Design; Direct Fit Oxygen Sensor |
| 1988 | BMW | 635CSi | 3.5L | L6 | Upstream | Cyls. 4-6; B2S1; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 1988 | BMW | M5 | 3.5L | L6 | Upstream | OE design oxygen sensor fits Bank 1 Sensor 1 for air/fuel ratio.; Direct Fit Oxygen Sensor |
| 1987 | BMW | 535i | 3.5L | L6 | Upstream | OE design oxygen sensor fits Bank 1 Sensor 1 for air/fuel ratio.; Direct Fit Oxygen Sensor |
| 1987 | BMW | 635CSi | 3.5L | L6 | Upstream | Cylinders 1-3, Bank 1 Sensor 1, OE Equivalent Design; Direct Fit Oxygen Sensor |
| 1987 | BMW | 635CSi | 3.5L | L6 | Upstream | Cyls. 4-6; B2S2; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 1987 | BMW | L6 | 3.5L | L6 | Upstream | B1S1; 3 Lead Sensor; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 1987 | BMW | L7 | 3.5L | L6 | Upstream | B1S1; 3 Lead Sensor; OE Equivalent Design; Direct Fit Oxygen Sensor |
| 1987 | BMW | M6 | 3.5L | L6 | Upstream | OE design oxygen sensor fits Bank 1 Sensor 1 for air/fuel ratio.; Direct Fit Oxygen Sensor |
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