11787589121 Front Upstream Oxygen Sensor for BMW 320i 328i 428i 528i X1 X3 X4 Z4 N20

◆ This front upstream oxygen sensor is a direct replacement for the original BMW unit, designed to measure exhaust oxygen content before the catalytic converter and provide feedback to the DME for fuel trim adjustment.

◆ The OEM reference number is 11787589121 (also written as 11 78 7 589 121). Cross-reference data lists 11787596908 and 11787613992 as related or interchangeable references.

◆ The sensor is a 5-wire wideband heated oxygen sensor with a wiring harness length of approximately 480 mm and an M18 x 1.5 thread, engineered to OEM standard dimensions for direct fitment into the upstream exhaust location.

◆ It is designed for a wide range of BMW models equipped with the N20/N26 2.0L turbocharged engine, including the 2 Series (F22/F23), 3 Series (F30/F31/F34), 4 Series (F32/F33/F36), 5 Series (F10), X1 (E84), X3 (F25), X4 (F26), X5 (F15) xDrive40e, and Z4 (E89).

◆ This product is an oxygen sensor manufactured to meet original quality standards for signal accuracy, fit, and durability.

◆ Part Number: 11787589121 / 11 78 7 589 121

◆ Related References: 11787596908, 11787613992

◆ Component Type: Oxygen Sensor / Front Upstream O2 Sensor (Wideband)

◆ Vehicle Make: BMW

◆ Engine Compatibility: N20 / N26 (2.0L Turbo)

◆ Wire Quantity: 5-wire

◆ Harness Length: Approx. 480 mm

◆ Thread Size: M18 x 1.5

◆ Position: Front / Upstream (before catalytic converter)

◆ Note: Verify connector shape and specific engine variant against your vehicle’s original sensor before ordering

◆ OEM Standard Fit: Manufactured to exact original specifications for a direct, hassle-free replacement.

◆ Upstream Fuel Trim Feedback: Measures exhaust oxygen content before the catalyst, enabling the DME to adjust fuel trim for optimal combustion and emissions.

◆ Wideband Heated Design: Integrated heater and wideband sensing element provide accurate air-fuel ratio data across the engine’s operating range.

◆ Durable Construction: Built with materials resistant to exhaust heat, contamination, and vibration.

◆ BMW 2 Series (F22/F23): 2014–2021 (228i, 228i xDrive)

◆ BMW 3 Series (F30/F31/F34): 2012–2019 (320i, 320i xDrive, 328i, 328i xDrive, 328i GT)

◆ BMW 4 Series (F32/F33/F36): 2014–2019 (428i, 428i xDrive, 428i Gran Coupe)

◆ BMW 5 Series (F10): 2011–2016 (528i, 528i xDrive)

◆ BMW X1 (E84): 2012–2015 (sDrive28i, xDrive28i)

◆ BMW X3 (F25): 2011–2017 (sDrive28i, xDrive28i)

◆ BMW X4 (F26): 2015–2018 (xDrive28i)

◆ BMW X5 (F15): 2016–2018 (xDrive40e)

◆ BMW Z4 (E89): 2012–2016 (sDrive28i)

◆ Note: Fitment varies by engine variant and market. Verify against your vehicle's original part number and production year before ordering.

Q1: Is this a genuine BMW part?

A: The 11787589121 reference is the original equipment part number. Both genuine BMW and aftermarket equivalents (such as NTK 24364 and other OE-quality suppliers) are available that match the original fit and function.

Q2: How do I confirm if it fits my vehicle?

A: Check your vehicle’s existing oxygen sensor. If it is stamped with 11787589121 or 11 78 7 589 121, this replacement will fit. Also confirm your vehicle is equipped with the N20/N26 2.0L engine and matches one of the models listed above. This is the upstream (front) sensor, positioned before the catalytic converter.

Q3: What are the symptoms of a failing upstream oxygen sensor?

A: Common signs include a check engine light with oxygen sensor or fuel trim fault codes, decreased fuel economy, rough idle, and hesitation during acceleration. Because the upstream sensor directly influences fuel delivery, failure can affect drivability and emissions performance. A diagnostic scan can confirm which sensor circuit is faulty before replacement.