Jerks on start and reverse (Cog with "!" sign)
I have 2000 323ci with 90,000 miles on it.
I just started getting jerks when I turn on the car and push the gas pedal upon accelerating from rest. Once it reach 10-15 mph, it is stable. After driving for a few minutes, I get a sign in the dashboard that is like a cog (circle with edges) containing an "!" sign. And then the car drives normally, but the sign stays on. When I am reversing the car, I feel the jerks all the time as long as I am reversing the car.
Any idea whats going on? I was reading on the internet and it could be due to low voltage to the transmission module and happens if I have a week or non OEM battery. I have a non OEM battery but I put that in about 2 years ago and never had any problems. The recommendation was to change the battery.
I took it to a mechanic and he said I need new transmissions.
Is there a way to tell if I really need new transmissions? Is it common for a 2000 bmw with 90000 miles, I thought bmw's can go on for a lot longer than that.
And if I really need new transmissions, how much should it cost approximately?
I am not very handy with cars so any advice / explanations are greatly appreciated.
Thanks in advance!