E46 B3S transmission system malfunction indicator

[graemel]

Hi guys. Just after your collective thoughts. About two months back I bought an Alpina B3S Cabriolet with 33,000 miles on the clock. I noticed a couple of weeks back, when I started the car that I had a cog type circle come up where the gear position indicator is. I turned the car off and back on and it cleared.
Today it did it again. Accept I did not immediately notice it until I started driving and the car felt very lethargic. So I pulled over. Turned it off, re started and all was fine.
The missus was with me and she said that it had happened to her a few times and that probably explains why she has on occasion complained the car felt very slow especially when pulling away.
I'll get it booked into Sytners next week. Thankfully I have a confirmed warranty.
Any thoughts on what this could be.
Many thanks for your help

[essayer]

It goes into limp mode and stays in one gear, which is why it feels sluggish.
Could be a number of reasons why it's throwing a fault, best thing is to get the codes read, that'll soon pinpoint the cause.