BMW E90 electrics cut out: main power cable connection melts
Why do the E90's electrics cut out completely and come back by themselves?
The cause is often the battery positive cable connection in the fuse box behind the glovebox. The connection loosens, oxidises or melts and heats up, so all power drops out for a moment. Replacing the battery alone does not fix the fault.
How is the main power cable connection repaired?
For the repair there is a repair cable with a new screw-fastened connector (part number 61129312133), so the whole cable does not need replacing if the fuse box is not badly burnt. Otherwise the fuse box is replaced. Locating the fault requires removing the fuse box, so the job is best left to a workshop.
Is there a recall for the main power cable?
In North America there was a recall for the 3 Series for model years 2007-2011. Coverage in Finland varies, so ask an authorised BMW dealer whether the car has a service action, and ask for the action number.