[marlboro64]

I have a 2007 328xi E91 and when I left my house this morning it started fine with no lights. On my second start multiple warning lights came on including some of the scary ones. After my initial freak out I started thinking that all these things couldn't all go at once.

I tried driving and everything seemed fine except the AC turned off, the windows wouldn't open and my blinkers stopped working. As I'm driving the warning lights are coming on and off. I can feel a noticeable loss of power til about 2k rpm and then it revs up normal.

When I got home I hooked up to INPA and pulled the codes below. Only the 4x4 light was on but I'm sure if I started driving the others would come up too. When the car if off all the electronics work fine.

Here are the codes. Any help would be appreciated.

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[lordnikon]

Is the alternator charging the battery?

[marlboro64]

Originally Posted by lordnikon

Is the alternator charging the battery?

Not sure … what’s the best way to test that?

[lordnikon]

Originally Posted by marlboro64

Not sure … what’s the best way to test that?

Use a multimeter and measure the battage voltage when the engine off and then on.

[marlboro64]

Originally Posted by lordnikon

Use a multimeter and measure the battery voltage when the engine off and then on.

Measure at the jump points in the engine bay.

Engine Off: 12.0V
Engine On: 13.5V

[BRG_N54]

Originally Posted by marlboro64

Not sure … what’s the best way to test that?

You can use the "hidden" menu on the gauge cluster to view voltage with the engine running. It should be between 13.5V-14.5V, any more or less and your voltage regulator is shot. $50US for new Bosch part and super easy to install.

[lordnikon]

Originally Posted by marlboro64

Measure at the jump points in the engine bay.

Engine Off: 12.0V
Engine On: 13.5V

The readings are borderline especially the battery.

Changing the voltage regular is a cheap fix but you have to take out the alternator to get access to it on the N52.

[marlboro64]

Originally Posted by lordnikon

The readings are borderline especially the battery.

Changing the voltage regular is a cheap fix but you have to take out the alternator to get access to it on the N52.

Was able to find a good deal on a rebuilt Bosch alternator with regulator. Going to drop it off at an Indy tomorrow and have them take a look.

At 190000km I’m pretty sure it’s in the original alternator.

Thanks for your help and I’ll update once I know more.

[marlboro64]

Woke up today to a completely dead battery and nothing turns on.

[lordnikon]

Are you able to jump it or trickle charge the battery overnight?

[skipraetor]

You may very well find that after replacing the alternator, battery, IBS, Kl 30 relay, final stage resistor, and ground strap that the battery holds a charge for longer but the issue never quite goes away. In case we are looking at the same issue as others in the e90 generation, please let me know if you've recently replaced the electric coolant pump and your oil level sensor shows "inactive." Right now I get 13.8v at the battery before the car reaches full operating temp, then it drops to 11.5. There's a chance you just have a ground strap issue and that will solve the parasitic draw but after doing a ton of reading I get the sense that the issue is not limited to just a poor ground, or that a poor ground might have led to a cascade of other issues.

I'm about to conduct a comprehensive test of the CAN Bus system with ISTA with the car hooked up to an external power supply. Thank you and good luck!