All modern Mercedes-Benz vehicles that have the original factory sound system have within the radio there is an electronic anti-theft feature that has a purpose of discouraging theives from going to their efforts to break into your vehicle to go to the effort to tear up the vehicle's dash to rip out a stereo system that will be in operable. So if someone was to remove the radio, the power is disconnected to it & the radio "locks up." When eventually power is supplied to the radio It would default to the word CODE on the main screen. All M-B vehicles came with a clear/with white lettering & the word CODE. They were affixed to each of the vehicle's rear windows as a prevention or discouragement to potential thieves as a reminder that the vehicle has a full alarm system & the radio would be useless to anyone (that is anyone without the correct CODE). Your vehicle may or may not still have the stickers, some owners remove them. The code is issued by M-B when the radio is installed & perhaps whenever it might default to the screen showing the word CODE it is asking for the numeric code that belongs to your radio & that number when entered will completely unlock the system & be fully functionable. When a M-B vehicle was new & being delivered to the original there was with the owner's manual a flexible silver/grey card with a numeric code for the radio. If you have access to your car's original owner's manual it still may be hidden within it or the folder. The Salesperson delivering the vehicle would have shown the owner the code card in the folder for the manuals & explained what the code was for & how to use it if necessary. Mercedes-Benz highly recommends that the owner remove the CODE card from thr manual & the entire vehicle & keep in another safe place...after all if the radio's un-locking code is available to someone stealing the radio ... having it in their posession defeats the security of the coded anti-theft deterrents ib place, so perhaps that might be a reason why you don't have it available. The only way to otherwise get the proper code is for you as a Registered Owner of the vehicle to go to any Authorized Merceded-Benz Dealership. You will need to bring the registration or similar document from your State"s Motor Vehicle Office that has your vehicle's VIN Number & you listed as a registered owner as proof of ownership along with your Photo Identification. You just visit the Parts or Service department show your vehicle's VIN & your Proof of Ownership & Valid Identification & the Dealership will look up your information & be able to provide you with the necessary code to un-lock your vehicle. If you needed a replacement key-fob-remote & key, you will need to do the same procedure with the same ownership/ID documents although you would need to pay for the remote & key.
Dont't forget that anytime 24/7 you could call M-B' toll free number (it's usually on the inside "vanity Light & Mirror) that is located on the Driver's sunvisor & ask any question regarding your vehicle & they will gladly explain what you need to know & even can send assistance to your location if need be. The M-B North American Headquarters ( that is who you will be speaking to), for security reasons I don't believe they would be able to give you the radio code in this situation but they would have been able to let you know that you would be able to get it from the Dealership as I have described. In any case this will be what you need for your car's radio & I wish you the best & many happy miles motoring in your roadster. Mike K