Artem, it is better to read the codes but your guess on the battery might not too far fetched either - my battery recently died, and i bought one on September 30, of all the places, from the wal-mart... i know, i know, but at that very moment, the local parts guys did not have the size in stock, i did not want to wait, so i got a 900 CCA battery from wal-mar, an H8 size, 3 year full replacement, 5 year pro-rated... tested out the door at 1015 CCA
3 weeks into service, the thing started to die... but, i did not get the signature tick-tick-tick that i would expect from a dying battery in a bimmer... i was getting a classic turn of a starter in a slow-mo, and then it would crank up and engine would start... i drove like that for a week, the situation was progressively worsening - after a nice long highway drive, the car would start fine, but few days later, an hour commute would not bring joy - the car would get slow-mo cranking 10 seconds after i park and shut off the motor... i even got a failsafe message or something...
took to walmart, they tested just over 700 CCA, took inside, charged it up for 20 minutes and the computer said it was good to go at 800 CCA.
tested the voltage with a simple voltmeter - at idle it registered about 14V (car's computer was at 13.8 - 13.9V)... as soon as engine was off, the system voltage dropping fast from 11.8V to 10.45V and stayed there...
I even disconnected the battery overnight, to rule out possible parasitic drain, the battery was at 10.4V in the morning - no extra drain in the car...
the interesting thing was, the battery still managed to start the engine, while it was clearly under the nominal voltage... I will look into this, just to see why it started the car...
long story short - went online, found a 15% coupon from Advance auto parts, bought a battery online from a local to me store, came to pick it - got AGM (or whatever that name is) 900 CCA, so far cranks up fast...
my point is, it could be your battery... i'd still get that software from that romanian dude... just for fun, you know...
