Car Completely Dead After New Battery

[slattrick]

I have a 2008 328i sedan with 120k miles, for the past few weeks it had some troubles starting and would crank for a few seconds on cold start but then start and have no problem when it was warmed up, changed the oil a few days ago after driving 3.5k miles since I got in January. After that it didn't have a problem starting so I thought that somehow fixed the problem. went to acme, got in my car and it wouldn't start or even crank. It would click however and all the lights worked, electronics were up, the bell would ring so I immediately thought it was a problem with the starter. Triple A guy came, tried to jump it, said that the battery was not giving enough power and should be replaced and then that should hopefully start it, I also read some forums with the same problem and my friend had a parent with the same problem in their e90 so I then went to replace the battery, got a new one, replaced it in the acme parking lot, made sure all the wires were hooked up to the battery. Nothing. Not even a click, all the electronics do not work, I have to use a key to open the door. Got it towed to my house and did some research and asked around, I have heard two things, 1) my car went into a "safe mode" or "lock down" and i need to spend the 320$ to get the computers reset or 2) I can replace a fuse (according to a friend with a dad who had a similar problem). But i have no clue. So please help cause i kinda need this car to run again for work. Thank You

[jclausen]

did you try another key, do all the dash lights come on

[PJLux]

I've heard you may have to "code" the new battery?

https://bmw-icom-a2-wifi.blogspot.co...ister-faq.html

[jclausen]

You have to register it not code it and the car would still run if it wasn't registered.

[evolandlupis]

"would crank for a few seconds on cold start but then start and have no problem when it was warmed up" , this part seems a bit concerning , I'd bet that the battery was low on charge, did you test the battery? do you by any chance have any external devices attached, alarms, aftermarket audio system? I can say more, but i'd need you to describe the exact steps you took to reproduce this. does it continue to experience this?

lowest cost to replace and quite troublesome often unthinked of is the IBS sensor / adapters literally right in front of the battery. i'd recommend swapping these out either way, just to rule it out, it's like $20.00 and maybe even cheaper at a junk yard.