Hello and welcome to JustAnswer BMW,My name is XXXXX XXXXX it will be my pleasure to assist you today.
what exactly happens when you try to start the car
thanks one moment please
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The first thing to do would be to check all fuses. Sometimes a very random blown fuse can cause this. Also you can unhook the car's battery for 1 hour to reset all systems.
Assuming the fuses are good, then there are a few things that can cause this. While not all can be trouble-shooted at home, I hope this information will be helpful to you and yield a possible solution.
1) bad key - try another one
2) bad brake light switch - make sure your brake lights work. If not, the switch is above the brake pedal.
3) bad immobilizer (aka EWS) - nothing can be done, dealer equipment is required to fix. When this goes bad or out of alignment, the car does not get the proper signal that the correct key is present, and therefore, the car will not start and the starter will not be allowed to engage.
4) issue with SMG control unit (SMG transmission only) not sending "safe to start" signal that the car is in neutral
5) bad clutch switch (manual transmission only, located above clutch pedal) - this is what signals the car that the clutch is depressed and is safe to start.
6) dead starter / solenoid - not likely, you would probably get some noise from it if this were the case.
7) bad ignition switch/cylinder - also unlikely as you would generally not get all other functions / power to come on inside the car in that case
Of course, it could also always be something totally random like a wiring breakage, but this is unlikely and hard to predict.
I hope that is helpful, please let me know if you have further questions, or if I can clarify anything for you.
It has been my pleasure to help today and I wish you the best of luck with the vehicle.
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