Where is the DSC sensor located on a 2007 530i?

There are a number of sensors in the DSC system. Which one do you want to know about. Four speeds sensors, steering angle sensor, low pressure sensor (on the hydraulic unit itself). are you throwing parts and guesses at this? Take it to an expert - it will cost you much less in the long run. It's like you are trying to diagnose a space-shuttle, except a later model BMW is generations ahead and more sophisticated... You should take this very sophisticated, technologically advanced piece of engineering beauty to a trained BMW Specialist (a specialist is someone who only works on one make of vehicle). There are many qualified independent, as well as dealer choices out there. Remember, there is no such thing as a Euro Specialist, or a Japanese Specialist, or a Domestic Specialist, or even a German Auto Specialist - the term would be an oxymoron. A German Auto Specialist would have to be proficient in seven different makes - this is not possible anymore "Jack of all trades, master of none". You can look up an excellent BMW shop by going to the BIMRS web directory (non-profit) at bimrs.org