Hi, welcome to Just answer! My name is Ross and i will help with your question
I am hear, dont worry!
Just wanted to ask a few questions to make sure i know whats going on with the auto stop.
Firstly, does the handbrake warning light work as normal?
No problem! Right, there is a whole hand full of possible problems that can cause this to happen so its a bit tricky for me to pinpoint it exactly. The most common is the battery, if the battery voltage is slightly lower than normal, it will prevent auto stop as this puts a lot of drain on the battery. Most garages will do a free battery check, alternatively if you have a charger, give it a good charge and see if it starts working.
No there is no single fuse that controls this system unfortunately. The battery is the most common cause, this often happens if you do a lot of short trips. otherwise it could be down to the clutch actuator switch or the ECU, i have known the ECU which is the main control unit to have problems, its usually a software problem in which case it needs to be plugged into a BMW Diagnostic system to check it and update the software if necessary. While it is plugged into this the clutch switch can be checked.
Unless you have a charger its best to take it to a garage. Most garages will do this for free anyway.
Good luck, hopefully it will be something simple. If you need to get back to me, please feel free i will be happy to help. If you happy with my answer, please don't forget to rate me service! Thanks, Ross.