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Bosch 15138 Oxygen Sensor - Downstream
| Brand | Bosch 15138 |
|---|---|
| Position | Downstream |
| Product line | Actual OE Oxygen Sensor |
| Fits | BMW · 11 vehicles |
Actual OE design. Built to match original equipment performance and fit expectations.
Narrow-band heated sensor. Provides precise air-fuel measurements and quicker closed-loop operation.
Ceramic sensing element. Delivers consistent accuracy under harsh heat and vibration.
Cross-references 11781406621 for the same application. See all 1.
Will it fit your vehicle?
Free return shipping if it doesn't fit.
Bosch OE Oxygen Sensor for BMW
Bosch 15138 is an Actual OE Oxygen Sensor built for precise air-fuel-ratio feedback to the ECU. It uses a narrow-band heated switching design to support stable combustion control and emissions management in the BMW applications listed below.
This Bosch Actual OE Oxygen Sensor line draws on Bosch’s long OE development history, including early thimble sensor designs and later planar narrowband technology for faster light-off and quicker closed-loop response. Bosch 15138 is a specific-fit replacement with a threaded metal housing, round female connector, and included wiring harness for direct service replacement.
- Fits 2006-2008 BMW Z4, downstream
- Fits 2001-2006 BMW M3, downstream
- Fits 2001-2002 BMW Z3, downstream
- Narrow-band heated oxygen sensor for closed-loop fuel control
- Specific-fit design with 4-wire configuration and 4-pin connector
- Threaded 18 mm sensor body with 22 mm hex size
- Wiring harness included for service replacement
- Cross-reference: BMW 11781406621
How Bosch 15138 Works
Bosch 15138 monitors exhaust oxygen content and sends a switching signal to the engine control unit so the fuel mixture can be adjusted accurately. In downstream locations on BMW Z4, BMW M3, and BMW Z3 applications, this sensor helps maintain proper catalyst monitoring and consistent emissions-system operation. The Bosch 15138 part number is commonly searched by owners looking for an OE-style downstream oxygen sensor replacement.
Common Issues This Sensor May Address
- Check engine light related to oxygen sensor performance
- Slow or inaccurate downstream O2 sensor response
- Rough combustion control caused by faulty exhaust feedback
- Emissions test failures tied to sensor degradation
- Incorrect air-fuel ratio readings reported to the ECU
Installation Notes
Verify the downstream location and connector style before installation. This sensor uses a threaded mount, 18 mm thread diameter, and a round female connector with four terminals. The harness length and overall sensor length should be checked against the original unit to confirm routing and reach on the BMW M3, BMW Z4, or BMW Z3 application.
Quality Assurance
Bosch supplies this Actual OE Oxygen Sensor as a standard replacement part built to OE-level specifications and materials. The design uses a heated narrow-band sensing element, ceramic construction, and high-temperature-resistant components for consistent operation under thermal and vibration load.
| Year | Make | Model | Liters | Cylinders | Position | Notes |
|---|---|---|---|---|---|---|
| 2008 | BMW | Z4 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
| 2007 | BMW | Z4 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
| 2006 | BMW | M3 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
| 2006 | BMW | Z4 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
| 2005 | BMW | M3 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
| 2004 | BMW | M3 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
| 2003 | BMW | M3 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
| 2002 | BMW | M3 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
| 2002 | BMW | Z3 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
| 2001 | BMW | M3 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
| 2001 | BMW | Z3 | 3.2L | L6 | Downstream | Cylinder(s) 1, 2, and 3; Actual OE Oxygen Sensor |
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