Hello, I've been having this message "chassis malfunction, or transmission malfunctions" they told me i was running are 245/45/20, and they suggested to go put 245/40/20, car running smooth for about couple days, and same issue again. I took it to BMW to get it diagnosed, and they told me there's some some miscommunication with the mechatronics. And I'm looking at 4200$

I need some help. Or If anyone know where i can get a cheap one?

thank you