Hey guys, I own a 2004 audi a4 quattro 1.8T.

This morning when it was about -30 after allowing the car to warm up, I threw it in drive and the car went into limp mode. Eventually throwing a check engine light and lighting all the symbols on the dashboard for the gears. So PRDS.
Upon restarting the engine the dash went back to normal. I checked the code and it came out as Po730, incorrect gear ratio. While I understand that possible causes for this may be insufficient transmission fluid. However what I truly wonder about at this point, is;

I am able to drive the car in manual (It's a tiptronic). Upon throwing it into manual the car jerks a little bit (Just once) and from there on its a normal drive.
Would insufficient transmission fluid still allow me to drive the car in manual or would it too go into safemode like the automatic portion of the car?

What function does the TCM have in comparison to the automatic and the manual portion of the gearbox, and would a faulty TCM still allow me to use the manual gearbox?

Do any of you have any ideas what could be the possible causes for this?