Genuine BMW Voltage Regulator - E60 M5, E63 M6, E90 335d

This part is listed by BMW as BMW part number 12318510092 (12-31-8-510-092) and is described as Genuine BMW Voltage Regulator for E60 M5, E63 M6, E90 335d. 

This voltage regulator was only used on a few applications here in the USA. That included the S85 V10 powered M5 and M6 (2006, 2007, 2008, 2009, and 2010) as well as the diesel powered E90 335d sedan, which was offered in 2009, 2010, and 2011. 

If your alternator is no longer maintaining a regular voltage (perhaps spiking well above the normal 13-15 volts DC), its very possible the voltage regulator (which is independently replaceable) is the culprit. If the voltage regulator fails, it can allow either no flow of electricity from the alternator/generator to the battery and charging system, OR in many cases it can cause the voltage to spike too high, causing issues and potentially greater damage, such a ruining a perfectly good BMW battery. 

While this doesn't cure all alternator / charging system woes, this is not a bad place to start before replacing the entire alternator (which is much more costly). 

For full BMW fitment information or for assistance from one of our BMW experts, we recommend calling us 877-639-9648.