SES light again

[sfcl]

I got the SES light about one month ago, the Peake scanner said that the throttle body failed, then the light went out and the engine ran fine for the last 2 weeks. Anyway I replaced the MAF for safety. Today, the SES light came again (no limp mode though), only when the engine is at idle speed and the idle was very rough. The Peake scanner said E4, E3, CA and CB which mean "02 sensor adaptation limit" for cylinders 1 tio 3 and same for cylinders 4 to 6, and "02 sensor control limit" for cylinders 1 to 3 and 4 to 6. No other codes.

Once again, the engine runs very well at any speed except idle. If I let it idling, it ends to, stall. If I keep the engine speed above 1500 rpm, no problem and it even clears the idle for some minutes until it becomes rough again.

Even if I had bad experiences with them in the past, I decided to go to the unique BMW dealer to get a diagnose with the right tool and wonder what, they can't check the vehicle with their software before.......October 27!!!

So, what do you (experts) think? Does the O2 sensors problem due to the sensors themselves or something else?

Thanks,