Will this fit my 2009 197..?

Yes it will physically fit, but you might want to pop out your existing stereo and see if the rear ISO blocks are similar.

The 197 normally has a stereo called "Update list" (bottom right hand corner) and these are MP3 (from a disc) CD and FM. They also have an Aux in on the back allowing for a ipod mp3 player connection (3.5mm jack)
 
That's the same one that came in my 200 so it should fit. From memory its the universal ISO connector block on the back of it. You may need an adaptor for the stalk controls to work though.