This part is listed by BMW as BMW part number 11289844643 (11 28 9 844 643) and is described as the main drive belt runs the water pump and alternator on B58C and B58D engines with the 48-volt Mild Hybrid system (MHT).
It's very important not to neglect your drive belts as a failure will leave you stranded. They're easy to inspect during normal maintenance such as an oil change or refilling your washer tank. If there are cracks running across the ribs, sections missing, the edges are frayed, or the threads are visible on the belt surface, the belt should be replaced immediately.
If you can, inspect and test the pulleys before ordering your belt(s) - tensioner, idler, water pump, and power steering. Also test the belt tensioner at the same time. Or plan to order new pulleys and tensioner with your belt(s). These pulleys are made of plastic and shatter with age, causing potentially expansive/expensive damage to your engine, radiator, etc. They usually last longer than the belt but now is the best time to replace them. Since they are bolted on, not pressed, they are easy to replace.
This is an OEM B58 serpentine belt manufactured by an original supplier to BMW for this part, as well as many other belts and components. As the OEM it meets all of BMW's original design, fitment, and performance requirements and is TUV approved. OEM parts are the best alternative to more expensive Original BMW parts because they are virtually identical without the inflated price tag. This part has a two year warranty.
BMW Fitments:
3 Series
G20 (2019+) > M340i
G20 (2019+) > M340i xDrive
4 Series
G22 / G23 (2021+) > M440i
G22 / G23 (2021+) > M440i xDrive
4 Series
G26 (2022+) > M440i xDrive Gran Coupe
5 Series
G30 (2017-2023) > 540i (B58C 2020-2023)
G30 (2017-2023) > 540i xDrive (B58C 2020-2023)
X3 Series
G01 X3 (2018+) > X3 M40i B58D (2020+)
X4 Series
G02 X4 (2019+) > X4 M40i B58D (2020+)
X5 Series
G05 X5 (2019+) > X5 xDrive40i B58C (2019-2023)
G05 X5 (2019+) > X5 sDrive40i RWD B58C (2019-2023)
X6 Series
G06 X6 (2020+) > X6 sDrive 40i B58C (2019-2023)
G06 X6 (2020+) > X6 xDrive 40i B58C (2019-2023)
X7 Series
G07 X7 (2019+) > X7 xDrive40i B58C (2019-2022)