Hello and thank you for using Just answer! I'm Billy and i will assist you with this. Feel free to ask if further info is needed.
I would suggest that you first check using a star scan tool (or equivalent).....a scan tool, that has good mercedes capabilities.
And if you still get the same code (C1140, C1540...which is a steering angle fault).......you should first and foremost check the steering sensor wiring and connector..........as this is the most common fault for this.,....so the sensor itself, is most likely good.
There is a bulletin issued by mercedes on that subject....which i will cinlude so you get the details:
click here for details
You should also check fuse F4 in dash fuse box......and the wiring and connectors of sensor (under steering wheel0.
You are advised to have a professional check this, as this requires disabling the airbag and removing....
Thank you for trusting JA and myself.......get back to me if further info is needed.....positive feedback and bonuses appreciated...http://www.justanswer.com/car/expert-billy/