With the engine running, scroll through the menu using the button(s) on the lower left side of the steering wheel. When you get to the page that says "1 Malfunction" use the arrow buttons to identify the cause. If it says something like "Tele-Aid/Please Activate", it simply means that there is no current subscription in effect for Tele-Aid service. This can be easily coded out using SDS. If it says "Tele-Aid Malfunction/Visit Workshop", that's another story. Some MB's will throw the warning in the event of a malfunction, even if Tele-Aid has been coded out. Legal reasons, or so I'm told.

The presence of a factory C-Tel system will have no effect, one way or another, on the malfunction display as far as warning messages are concerned.