In my BMW 320i airbag signal is on why

The airbag and the alternator may have been caused by a drive belt failing on the engine, this would cause an overheat, I hope you did not drive it very far as this engine can be ruined by excessive overheating. Look under the hood and see if the drive belt is on the engine.

check for broken alternator drive belt
if broken the battery will be flat

You have a check light on & thus a system fault & codes

Retrieve the codes,nothing new there,same as every
vehicle issue

Then you need a shop to diagnose the problem

You must get the electronic engine control module scanned, when this light is turned on a fault code is stored in the control modules memory.

Car not starting or turning over indicates towards multiple possibilities. It can be issue with battery or weak battery. But if battery checks out ok, then it can be starter issue or faulty alternator or problem with low fuel pressure or no spark at spark plugs due to dirty spark plugs or faulty ignition coil or injectors getting cracked or dirty and needs to be cleaned.

To confirm the problem, the basic troubleshooting is required.

Click this link below and follow the troubleshooting:------

http://technoanswers.blogspot.in/2012/02/car-starting-issues.html

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This will help.
Thanks.

The computer needs 12V in order to start.

If the airbag (SRS) light is on then it means there is a problem with the system. Working on the SRS can be very hazardous. For this reason I suggest you have this looked at by a professional. This is not a DIY repair. Far too dangerous for a novice to attempt to repair.

Hey,
take a look at www.airbagmodul.com

They're working in Airbag-Simulators and Occupancy Sensor-Simulators.

Regards

Gerrit

Your oil is a little low, and the timing may be off a bit but if it smooths out after warm it is probably ljust
low oil.

was your BMW over heated?