A common problem you'll probably deal with on your E60 M5 is the so called SZL failure. That stands for 'steering angle sensor' and when you'll encounter it it will manifest itself quite obviously.
What will happen is after starting your car at the first instance of turning the steering wheel left or right, you'll get errors indicating faults with the DSC and FTM. When this happens, you're in trouble.
It's not serious trouble though. Actually, it's something you can fix with one dollar and a couple of hours of work. So, what you have to do is pull out the steering angle sensor (it looks like a disk) and clean it. Sounds easy enough but it isn't.
In order to reach that sensor you'll have to take apart almost all of the steering column, including the steering wheel and the airbags. Don't be afraid though, this step by step DIY will guide you through the process. Good luck!
Via: M5Board.com
It's not serious trouble though. Actually, it's something you can fix with one dollar and a couple of hours of work. So, what you have to do is pull out the steering angle sensor (it looks like a disk) and clean it. Sounds easy enough but it isn't.
In order to reach that sensor you'll have to take apart almost all of the steering column, including the steering wheel and the airbags. Don't be afraid though, this step by step DIY will guide you through the process. Good luck!
Via: M5Board.com