Q: Red gear/ sprocket + exclamation warning light. when I scan it the code AOB1 comes out with the message: CAS:input selector lever

The red gear symbol is the transmission version of a check engine light. It alerts you that a fault has been detected by the transmission controller. The "gear selector implausible" message means that the controller cannot make sense of some of the input signals it is seeing. Your transmission is electronically controlled and right now, for some reason the controller can’t figure out what you want to do. The gear selector has a switch that tells the controller what position it is in, but there are other sensors in the system that don’t agree with what the gear selector sensor is saying. This doesn’t seem to be a common enough failure to have formed a pattern, so It’s going to take some diagnostic work by someone with the appropriate scan equipment. You can have this done right there at your home or office by contacting Your Mechanic. They will send a technician to you who can check out your BMW and let you know what it’s going to take to solve the problem.