Just noticed this today... don't know what it is...

Turn the key, engine starts, i hear bad buzzing noise from under the car, engine aria, car engine just shuts off... it doesn't sputter, doesn't do anything else just... dead.

I turn the key again, engine starts, buzzes, and keeps running.

Its done this three times today, every time its the same...
turn, start, buzz, die... turn, start,buzz keeps going...

id like to nip this in the bud before I get stranded somewhere. .

Thanks guys