Merry Christmas and Happy Holidays everyone!

I am trying to diagnose a scary electrical issue with my 2007 E92 330i.

The Main Symptoms:

1. Sudden Power Cut: While driving, the car suddenly cuts throttle/power. At that exact moment, the Service Light flashes briefly, and the transmission throws code CF25 (EGS: Message from engine control Alive signal fault).

• Note: I used to get CF1C, but now it is consistently CF25.

2. Hesitant Crank: When starting the car, the starter turns for a split second, pauses/stops completely, and then continues to turn sluggishly until the engine fires.

3. Sensor Dropouts: My AFR readings (O2 sensor) appear and disappear intermittently.

I really need help, battery voltage is 12.4 when is off, when is on 13.9-14.1 v

And also I was not at home for 19 days and battery was still alive after 19 days so I think its not the battery.

But another problem is when i turn it off and lock it , the park light on shifter doesnt turn off, even after 19 days it was on.

Edited 6 hours ago6 hr by twinntrbo

Happy Christmas Firat

Welcome to the Forum

First thoughts a Starter or Alternator issue, here are my thoughts

1. Battery Voltage at rest should be at least 12.5v (lower shows a drain or battery issue) with the engine running 14.6+v (lower would indicate slow or low charge from the Alternator)

2. The fact the car isn't going to sleep (gear indicator still lit)

3. There was an issue with Magneti Marelli starter around your vintage which caused huge Amp draw at start and eventually killed batteries

(1) Fully Charge the battery at the charge points under the bonnet as said should read 12.5+v (2) Needs investigation could be a Can Bus issue (3) Check amperage at start with a clamp Ammeter I saw one that pulled 700+amps

Last but not least get a full Diagnostic scan done using a BMW capable programme best is BMW ISTA/INPA then Foxwell, Autologic iCarsoft or similar. My reasoning here is I can't believe there are not hidden faults particularly as there is a possible can bus issue

We know what you want for Christmas 😅 Have a good one

Dave

Thank you Dave,

Then what do you think about cf25 fault? I tought it was a transmission issue,